Categories
Vue Answers

How to add web workers to a Vue app created with Vue-CLI?

Sometimes, we want to add web workers to a Vue app created with Vue-CLI.

In this article, we’ll look at how to add web workers to a Vue app created with Vue-CLI.

How to add web workers to a Vue app created with Vue-CLI?

To add web workers to a Vue app created with Vue-CLI, we can use the worker-plugin package.

To install it, we run:

npm i worker-plugin

Next, ion vue.config.js in the project root, we add:

const WorkerPlugin = require("worker-plugin");

module.exports = {
  configureWebpack: {
    output: {
      globalObject: "this"
    },
    plugins: [new WorkerPlugin()]
  }
};

to load the worker-plugin.

Then we create the workers folder in the src folder with the following 2 files:

worker.js

onmessage = (e) => {
  const {data} = e
  console.log(data);
  postMessage({ foo: "bar" });
};

We call postMessage to send a message to the component that invoked the worker.

index.js

const worker = new Worker("./worker.js", { type: "module" });

const send = (message) =>
  worker.postMessage({
    message
  });

export default {
  worker,
  send
};

Next, we use the worker in a component by writing the following in src/App.vue:

<template>
  <div id="app"></div>
</template>

<script>
import w from "@/workers";

export default {
  name: "App",
  beforeMount() {
    const { worker, send } = w;
    worker.onmessage = (e) => {
      const { data } = e;
      console.log(data);
    };
    send({ foo: "baz" });
  },
};
</script>

We import the workers/index.js with:

import w from "@/workers";

Then we destructure the worker from the imported module with:

const { worker, send } = w;

Then we add a message handler to it with:

worker.onmessage = (e) => {
  const { data } = e;
  console.log(data);
};

And then we send a message to the worker with:

send({ foo: "baz" });

Now we get {foo: 'bar'} from the worker in the worker.onmessage in App.

And in worker.js‘s onmessage function, we get:

{
  message: {
    foo: 'baz'
  }
}

Conclusion

To add web workers to a Vue app created with Vue-CLI, we can use the worker-plugin package.

Categories
JavaScript Nuxt.js Vue

How to run background tasks in a Nuxt app with web workers?

(The source code is at https://github.com/jauyeunggithub/bravado-quest)

Sometimes, we want to run background tasks in a Nuxt app with web workers.

In this article, we’ll look at how to run background tasks in a Nuxt app with web workers.

How to run background tasks in a Nuxt app with web workers?

To run background tasks in a Nuxt app with web workers, we can add the Webpack’s worker-loader package into our Nuxt project.

Also, we’ve to make sure that web workers are only loaded on client side.

We’ll make a project that loads a large JSON file and searches it.

To start, we create the Nuxt project with:

npx create-nuxt-app quest

Then we run:

cd quest
npm run dev

to change to the project folder and run the project.

Next, we add Vuetify into the project with:

npm install @nuxtjs/vuetify -D

And we add the worker-loader package with:

npm i worker-loader@^1.1.1

To store data with IndexedDB, we install the Dexie package.

To install it, we run:

npm i dexie

Next, in nuxt.config.js, we change it to:

export default {
  // Global page headers: https://go.nuxtjs.dev/config-head
  head: {
    title: 'quest',
    htmlAttrs: {
      lang: 'en',
    },
    meta: [
      { charset: 'utf-8' },
      { name: 'viewport', content: 'width=device-width, initial-scale=1' },
      { hid: 'description', name: 'description', content: '' },
      { name: 'format-detection', content: 'telephone=no' },
    ],
    link: [{ rel: 'icon', type: 'image/x-icon', href: '/favicon.ico' }],
  },

  // Global CSS: https://go.nuxtjs.dev/config-css
  css: [],

  // Plugins to run before rendering page: https://go.nuxtjs.dev/config-plugins
  plugins: [
    { src: '~/plugins/inject-ww', ssr: false }
  ],

  // Auto import components: https://go.nuxtjs.dev/config-components
  components: true,

  // Modules for dev and build (recommended): https://go.nuxtjs.dev/config-modules
  buildModules: ['@nuxtjs/vuetify'],

  // Modules: https://go.nuxtjs.dev/config-modules
  modules: [],

  // Build Configuration: https://go.nuxtjs.dev/config-build
  mode: 'spa',
  build: {
    extend(config, { isClient }) {
      config.output.globalObject = 'this'

      if (isClient) {
        config.module.rules.push({
          test: /\.worker\.js$/,
          loader: 'worker-loader',
          exclude: /(node_modules)/,
        })
      }
    },
  },
  ssr: false,
}

We added the build.extend method to invoke the worker-loader when any file that ends with .worker.js is found.

isClient makes sure workers only load on client side apps.

config.output.globalObject = 'this' is needed so the hot reloading will work with the web workers loaded.

We also set ssr to false to disable server side rendering.

Also, we add { src: '~/plugins/inject-ww', ssr: false } to add the /plugins/inject-ww to load the worker loading plugin.

We add '@nuxtjs/vuetify' to load Vuetify in Nuxt.

In the plugins folder, we add:

import Worker from '~/assets/js/data.worker.js'

export default (_, inject) => {
  inject('worker', {
    createWorker () {
      return new Worker()
    }
  })
}

to load the worker from the /assets/js/data.worker.js.

To create worker, we create the data.worker.js file in the /assets/js/ and add:

import db from '@/db'

onmessage = async () => {
  if ((await db.avatars.toCollection().toArray()).length > 0) {
    postMessage({
      loaded: true,
    })
    return
  }
  const usersObj = await import(`@/data/users.json`)
  const users = Object.values(usersObj)
  const usersWithId = users.map((u, id) => ({ ...u, id }))
  await db.avatars.bulkPut(usersWithId)
  postMessage({
    loaded: true,
  })
}

@/data/users.json is a big JSON file saved in the project.

We import the users.json file from the data folder and store it in Indexed DB with Dexie.

db comes from db.js, which has:

import Dexie from 'dexie'

const db = new Dexie('db')
db.version(1).stores({
  avatars: '++id, address, avatar, city, email, name, title',
})

export default db

We create the db database with the avatars collection with the given keys.

We call bulkPut to write the retrieved data to the collection.

And we call postMessage to communicate that loading is done.

The message will be picked by by the message event handler when we invoke this worker.

In the pages, folder, we add _keyword.vue, to add an input and the search results component:

<template>
  <v-app>
    <v-card width="600px" elevation="0" class="mx-auto">
      <v-card-text :elevation="0">
        <v-text-field
          v-model="keyword"
          hide-details
          :prepend-inner-icon="mdiMagnify"
          full-width
          solo
          dense
          background-color="#FAFAFA"
        />

        <SearchResults :keyword="keyword" />
      </v-card-text>
    </v-card>
  </v-app>
</template>

<script >
import { mdiMagnify } from '@mdi/js'
import SearchResults from '@/components/SearchResults'

export default {
  components: {
    SearchResults,
  },
  data() {4
    return {
      keyword: '',
      mdiMagnify,
    }
  },
  beforeMount() {
    this.keyword = this.$route.params.keyword
  },
}
</script>

<style>
html {
  overflow: hidden;
}
</style>

Then in components/SearchResults.vue that we created, we add:

<template>
  <div>
    <div v-if="loading" class="my-3">
      <v-card>
        <v-card-text> Loading... </v-card-text>
      </v-card>
    </div>
    <div v-else id="scrollable" class="my-3">
      <v-card
        v-for="r of filteredSearchResultsWithHighlight"
        :key="r.id"
        class="my-3"
        :style="{
          border: highlightStatus[r.id] ? '2px solid lightblue' : undefined,
        }"
        @click="
          highlightStatus = {}
          $set(highlightStatus, r.id, !highlightStatus[r.id])
        "
      >
        <v-card-text class="d-flex pa-0 ma-0">
          <img :src="r.avatar" class="avatar" />
          <div
            class="flex-grow-1 pa-3 d-flex flex-column justify-space-between right-pane"
          >
            <div class="d-flex justify-space-between">
              <div>
                <h2 v-html="r.name"></h2>
                <p class="py-0 my-0">
                  <b v-html="r.title"></b>
                </p>
                <p class="py-0 my-0">
                  <span v-html="r.address"></span>,
                  <span v-html="r.city"></span>
                </p>
              </div>
              <div v-html="r.email"></div>
            </div>

            <div>
              <v-btn text color="#00897B">Mark as Suitable</v-btn>
            </div>
          </div>
        </v-card-text>
      </v-card>
    </div>
  </div>
</template>

<script>
import db from '@/db'

export default {
  props: {
    keyword: {
      type: String,
      default: '',
    },
  },
  data() {
    return {
      highlightStatus: {},
      filteredSearchResults: [],
      loading: false,
    }
  },
  computed: {
    filteredSearchResultsWithHighlight() {
      const { keyword } = this
      if (!Array.isArray(this.filteredSearchResults)) {
        return []
      }
      const highlighted = this.filteredSearchResults?.map((u) => {
        const highlightedEntries = Object.entries(u)?.map(([key, val]) => {
          if (key === 'avatar' || key === 'id') {
            return [key, val]
          }
          const highlightedVal = val?.replace(
            new RegExp(keyword, 'gi'),
            (match) => `<mark>${match}</mark>`
          )
          return [key, highlightedVal]
        })
        return Object.fromEntries(highlightedEntries)
      })
      return highlighted
    },
  },
  watch: {
    keyword: {
      immediate: true,
      handler() {
        this.search()
      },
    },
  },
  beforeMount() {
    this.loadData()
  },
  methods: {
    async search() {
      await this.$nextTick()
      const { keyword } = this
      if (keyword) {
        const filteredSearchResults = await db.avatars
          .filter((u) => {
            const { address, city, email, name, title } = u
            return (
              address?.toLowerCase()?.includes(keyword?.toLowerCase()) ||
              city?.toLowerCase()?.includes(keyword?.toLowerCase()) ||
              email?.toLowerCase()?.includes(keyword?.toLowerCase()) ||
              name?.toLowerCase()?.includes(keyword?.toLowerCase()) ||
              title?.toLowerCase()?.includes(keyword?.toLowerCase())
            )
          })
          .limit(10)
          .toArray()
        this.filteredSearchResults = filteredSearchResults
      } else {
        this.filteredSearchResults = await db.avatars
          ?.toCollection()
          ?.limit(10)
          .toArray()
      }
    },
    loadData() {
      this.loading = true
      const worker = this.$worker.createWorker()
      worker.onmessage = () => {
        this.search()
        this.loading = false
      }
      worker.postMessage('load')
    },
  },
}
</script>

<style>
.avatar {
  background: #bdbdbd;
  width: 150px;
}

.right-pane {
  background: #fafafa;
}

mark {
  background: yellow;
}

#scrollable {
  height: calc(100vh - 100px);
  overflow-y: auto;
}
</style>

In the loadData method. we call this.$worker.createWorker to create the worker that we injected.

this.$worker is available since the inject-ww.js script is run when the app is loaded.

We set worker.onmessage to a function so that we recent messages from the worker when postMessage in the onmessage function of the worker is called.

Once we received a message from the web workwer, we call the this.search method to do the filtering according to the keyword value.

And we call worker.postMessage with anything so that the worker’s onmessage function in the worker will start running.

Now when we type in something into the text box, we see results displayed in the cards.

We should be able to load large amounts of data in the web worker without hanging the browser since it’s run in the background.

Conclusion

To run background tasks in a Nuxt app with web workers, we can add the Webpack’s worker-loader package into our Nuxt project.

Also, we’ve to make sure that web workers are only loaded on client side.

We’ll make a project that loads a large JSON file and searches it.

Categories
JavaScript Nuxt.js

How to load large amounts of data in the background in a Nuxt app with web workers?

(The source code is at https://github.com/jauyeunggithub/bravado-quest)

Sometimes, we want to load large amounts of data in the background in a Nuxt app with web workers

In this article, we’ll look at how to load large amounts of data in the background in a Nuxt app with web workers

How to load large amounts of data in the background in a Nuxt app with web workers?

To run background tasks in a Nuxt app with web workers, we can add the Webpack’s worker-loader package into our Nuxt project.

Also, we’ve to make sure that web workers are only loaded on client side.

We’ll make a project that loads a large JSON file and searches it.

To start, we create the Nuxt project with:

npx create-nuxt-app quest

Then we run:

cd quest
npm run dev

to change to the project folder and run the project.

Next, we add Vuetify into the project with:

npm install @nuxtjs/vuetify -D

And we add the worker-loader package with:

npm i worker-loader@^1.1.1

To store data with IndexedDB, we install the Dexie package.

To install it, we run:

npm i dexie

Next, in nuxt.config.js, we change it to:

export default {
  // Global page headers: https://go.nuxtjs.dev/config-head
  head: {
    title: 'quest',
    htmlAttrs: {
      lang: 'en',
    },
    meta: [
      { charset: 'utf-8' },
      { name: 'viewport', content: 'width=device-width, initial-scale=1' },
      { hid: 'description', name: 'description', content: '' },
      { name: 'format-detection', content: 'telephone=no' },
    ],
    link: [{ rel: 'icon', type: 'image/x-icon', href: '/favicon.ico' }],
  },

  // Global CSS: https://go.nuxtjs.dev/config-css
  css: [],

  // Plugins to run before rendering page: https://go.nuxtjs.dev/config-plugins
  plugins: [
    { src: '~/plugins/inject-ww', ssr: false }
  ],

  // Auto import components: https://go.nuxtjs.dev/config-components
  components: true,

  // Modules for dev and build (recommended): https://go.nuxtjs.dev/config-modules
  buildModules: ['@nuxtjs/vuetify'],

  // Modules: https://go.nuxtjs.dev/config-modules
  modules: [],

  // Build Configuration: https://go.nuxtjs.dev/config-build
  mode: 'spa',
  build: {
    extend(config, { isClient }) {
      config.output.globalObject = 'this'

      if (isClient) {
        config.module.rules.push({
          test: /\.worker\.js$/,
          loader: 'worker-loader',
          exclude: /(node_modules)/,
        })
      }
    },
  },
  ssr: false,
}

We added the build.extend method to invoke the worker-loader when any file that ends with .worker.js is found.

isClient makes sure workers only load on client side apps.

config.output.globalObject = 'this' is needed so the hot reloading will work with the web workers loaded.

We also set ssr to false to disable server side rendering.

Also, we add { src: '~/plugins/inject-ww', ssr: false } to add the /plugins/inject-ww to load the worker loading plugin.

We add '@nuxtjs/vuetify' to load Vuetify in Nuxt.

In the plugins folder, we add:

import Worker from '~/assets/js/data.worker.js'

export default (_, inject) => {
  inject('worker', {
    createWorker () {
      return new Worker()
    }
  })
}

to load the worker from the /assets/js/data.worker.js.

To create worker, we create the data.worker.js file in the /assets/js/ and add:

import db from '@/db'

onmessage = async () => {
  if ((await db.avatars.toCollection().toArray()).length > 0) {
    postMessage({
      loaded: true,
    })
    return
  }
  const usersObj = await import(`@/data/users.json`)
  const users = Object.values(usersObj)
  const usersWithId = users.map((u, id) => ({ ...u, id }))
  await db.avatars.bulkPut(usersWithId)
  postMessage({
    loaded: true,
  })
}

@/data/users.json is a big JSON file saved in the project.

We import the users.json file from the data folder and store it in Indexed DB with Dexie.

We can load very large JSON files without crashing the browser since web workers run in a separate thread from the main browser thread.

db comes from db.js, which has:

import Dexie from 'dexie'

const db = new Dexie('db')
db.version(1).stores({
  avatars: '++id, address, avatar, city, email, name, title',
})

export default db

We create the db database with the avatars collection with the given keys.

We call bulkPut to write the retrieved data to the collection.

Now we cache the data in Indexed DB so they don’t have to load every time we load the app.

We make sure we try to load the cached data first with:

if ((await db.avatars.toCollection().toArray()).length > 0) {
  postMessage({
    loaded: true,
  })
  return
}

And we call postMessage to communicate that loading is done.

The message will be picked by by the message event handler when we invoke this worker.

In the pages, folder, we add _keyword.vue, to add an input and the search results component:

<template>
  <v-app>
    <v-card width="600px" elevation="0" class="mx-auto">
      <v-card-text :elevation="0">
        <v-text-field
          v-model="keyword"
          hide-details
          :prepend-inner-icon="mdiMagnify"
          full-width
          solo
          dense
          background-color="#FAFAFA"
        />

        <SearchResults :keyword="keyword" />
      </v-card-text>
    </v-card>
  </v-app>
</template>

<script >
import { mdiMagnify } from '@mdi/js'
import SearchResults from '@/components/SearchResults'

export default {
  components: {
    SearchResults,
  },
  data() {4
    return {
      keyword: '',
      mdiMagnify,
    }
  },
  beforeMount() {
    this.keyword = this.$route.params.keyword
  },
}
</script>

<style>
html {
  overflow: hidden;
}
</style>

Then in components/SearchResults.vue that we created, we add:

<template>
  <div>
    <div v-if="loading" class="my-3">
      <v-card>
        <v-card-text> Loading... </v-card-text>
      </v-card>
    </div>
    <div v-else id="scrollable" class="my-3">
      <v-card
        v-for="r of filteredSearchResultsWithHighlight"
        :key="r.id"
        class="my-3"
        :style="{
          border: highlightStatus[r.id] ? '2px solid lightblue' : undefined,
        }"
        @click="
          highlightStatus = {}
          $set(highlightStatus, r.id, !highlightStatus[r.id])
        "
      >
        <v-card-text class="d-flex pa-0 ma-0">
          <img :src="r.avatar" class="avatar" />
          <div
            class="flex-grow-1 pa-3 d-flex flex-column justify-space-between right-pane"
          >
            <div class="d-flex justify-space-between">
              <div>
                <h2 v-html="r.name"></h2>
                <p class="py-0 my-0">
                  <b v-html="r.title"></b>
                </p>
                <p class="py-0 my-0">
                  <span v-html="r.address"></span>,
                  <span v-html="r.city"></span>
                </p>
              </div>
              <div v-html="r.email"></div>
            </div>

            <div>
              <v-btn text color="#00897B">Mark as Suitable</v-btn>
            </div>
          </div>
        </v-card-text>
      </v-card>
    </div>
  </div>
</template>

<script>
import db from '@/db'

export default {
  props: {
    keyword: {
      type: String,
      default: '',
    },
  },
  data() {
    return {
      highlightStatus: {},
      filteredSearchResults: [],
      loading: false,
    }
  },
  computed: {
    filteredSearchResultsWithHighlight() {
      const { keyword } = this
      if (!Array.isArray(this.filteredSearchResults)) {
        return []
      }
      const highlighted = this.filteredSearchResults?.map((u) => {
        const highlightedEntries = Object.entries(u)?.map(([key, val]) => {
          if (key === 'avatar' || key === 'id') {
            return [key, val]
          }
          const highlightedVal = val?.replace(
            new RegExp(keyword, 'gi'),
            (match) => `<mark>${match}</mark>`
          )
          return [key, highlightedVal]
        })
        return Object.fromEntries(highlightedEntries)
      })
      return highlighted
    },
  },
  watch: {
    keyword: {
      immediate: true,
      handler() {
        this.search()
      },
    },
  },
  beforeMount() {
    this.loadData()
  },
  methods: {
    async search() {
      await this.$nextTick()
      const { keyword } = this
      if (keyword) {
        const filteredSearchResults = await db.avatars
          .filter((u) => {
            const { address, city, email, name, title } = u
            return (
              address?.toLowerCase()?.includes(keyword?.toLowerCase()) ||
              city?.toLowerCase()?.includes(keyword?.toLowerCase()) ||
              email?.toLowerCase()?.includes(keyword?.toLowerCase()) ||
              name?.toLowerCase()?.includes(keyword?.toLowerCase()) ||
              title?.toLowerCase()?.includes(keyword?.toLowerCase())
            )
          })
          .limit(10)
          .toArray()
        this.filteredSearchResults = filteredSearchResults
      } else {
        this.filteredSearchResults = await db.avatars
          ?.toCollection()
          ?.limit(10)
          .toArray()
      }
    },
    loadData() {
      this.loading = true
      const worker = this.$worker.createWorker()
      worker.onmessage = () => {
        this.search()
        this.loading = false
      }
      worker.postMessage('load')
    },
  },
}
</script>

<style>
.avatar {
  background: #bdbdbd;
  width: 150px;
}

.right-pane {
  background: #fafafa;
}

mark {
  background: yellow;
}

#scrollable {
  height: calc(100vh - 100px);
  overflow-y: auto;
}
</style>

In the loadData method. we call this.$worker.createWorker to create the worker that we injected.

this.$worker is available since the inject-ww.js script is run when the app is loaded.

We set worker.onmessage to a function so that we recent messages from the worker when postMessage in the onmessage function of the worker is called.

Once we received a message from the web workwer, we call the this.search method to do the filtering according to the keyword value.

And we call worker.postMessage with anything so that the worker’s onmessage function in the worker will start running.

Now when we type in something into the text box, we see results displayed in the cards.

We should be able to load large amounts of data in the web worker without hanging the browser since it’s run in the background.

Conclusion

To run background tasks in a Nuxt app with web workers, we can add the Webpack’s worker-loader package into our Nuxt project.

Also, we’ve to make sure that web workers are only loaded on client side.

We’ll make a project that loads a large JSON file and searches it.

Categories
Nuxt.js Vue Answers

How to access route parameters in a page with Nuxt?

(The source code is at https://github.com/jauyeunggithub/bravado-quest)

Sometimes, we want to load large amounts of data in the background in a Nuxt app with web workers

In this article, we’ll look at how to load large amounts of data in the background in a Nuxt app with web workers

How to access route parameters in a page with Nuxt?

To run background tasks in a Nuxt app with web workers, we can add the Webpack’s worker-loader package into our Nuxt project.

Also, we’ve to make sure that web workers are only loaded on client side.

We’ll make a project that loads a large JSON file and searches it.

To start, we create the Nuxt project with:

npx create-nuxt-app quest

Then we run:

cd quest
npm run dev

to change to the project folder and run the project.

Next, we add Vuetify into the project with:

npm install @nuxtjs/vuetify -D

And we add the worker-loader package with:

npm i worker-loader@^1.1.1

To store data with IndexedDB, we install the Dexie package.

To install it, we run:

npm i dexie

Next, in nuxt.config.js, we change it to:

export default {
  // Global page headers: https://go.nuxtjs.dev/config-head
  head: {
    title: 'quest',
    htmlAttrs: {
      lang: 'en',
    },
    meta: [
      { charset: 'utf-8' },
      { name: 'viewport', content: 'width=device-width, initial-scale=1' },
      { hid: 'description', name: 'description', content: '' },
      { name: 'format-detection', content: 'telephone=no' },
    ],
    link: [{ rel: 'icon', type: 'image/x-icon', href: '/favicon.ico' }],
  },

  // Global CSS: https://go.nuxtjs.dev/config-css
  css: [],

  // Plugins to run before rendering page: https://go.nuxtjs.dev/config-plugins
  plugins: [
    { src: '~/plugins/inject-ww', ssr: false }
  ],

  // Auto import components: https://go.nuxtjs.dev/config-components
  components: true,

  // Modules for dev and build (recommended): https://go.nuxtjs.dev/config-modules
  buildModules: ['@nuxtjs/vuetify'],

  // Modules: https://go.nuxtjs.dev/config-modules
  modules: [],

  // Build Configuration: https://go.nuxtjs.dev/config-build
  mode: 'spa',
  build: {
    extend(config, { isClient }) {
      config.output.globalObject = 'this'

      if (isClient) {
        config.module.rules.push({
          test: /\.worker\.js$/,
          loader: 'worker-loader',
          exclude: /(node_modules)/,
        })
      }
    },
  },
  ssr: false,
}

We added the build.extend method to invoke the worker-loader when any file that ends with .worker.js is found.

isClient makes sure workers only load on client side apps.

config.output.globalObject = 'this' is needed so the hot reloading will work with the web workers loaded.

We also set ssr to false to disable server side rendering.

Also, we add { src: '~/plugins/inject-ww', ssr: false } to add the /plugins/inject-ww to load the worker loading plugin.

We add '@nuxtjs/vuetify' to load Vuetify in Nuxt.

In the plugins folder, we add:

import Worker from '~/assets/js/data.worker.js'

export default (_, inject) => {
  inject('worker', {
    createWorker () {
      return new Worker()
    }
  })
}

to load the worker from the /assets/js/data.worker.js.

To create worker, we create the data.worker.js file in the /assets/js/ and add:

import db from '@/db'

onmessage = async () => {
  if ((await db.avatars.toCollection().toArray()).length > 0) {
    postMessage({
      loaded: true,
    })
    return
  }
  const usersObj = await import(`@/data/users.json`)
  const users = Object.values(usersObj)
  const usersWithId = users.map((u, id) => ({ ...u, id }))
  await db.avatars.bulkPut(usersWithId)
  postMessage({
    loaded: true,
  })
}

@/data/users.json is a big JSON file saved in the project.

We import the users.json file from the data folder and store it in Indexed DB with Dexie.

We can load very large JSON files without crashing the browser since web workers run in a separate thread from the main browser thread.

db comes from db.js, which has:

import Dexie from 'dexie'

const db = new Dexie('db')
db.version(1).stores({
  avatars: '++id, address, avatar, city, email, name, title',
})

export default db

We create the db database with the avatars collection with the given keys.

We call bulkPut to write the retrieved data to the collection.

Now we cache the data in Indexed DB so they don’t have to load every time we load the app.

We make sure we try to load the cached data first with:

if ((await db.avatars.toCollection().toArray()).length > 0) {
  postMessage({
    loaded: true,
  })
  return
}

And we call postMessage to communicate that loading is done.

The message will be picked by by the message event handler when we invoke this worker.

In the pages, folder, we add _keyword.vue, to add an input and the search results component:

<template>
  <v-app>
    <v-card width="600px" elevation="0" class="mx-auto">
      <v-card-text :elevation="0">
        <v-text-field
          v-model="keyword"
          hide-details
          :prepend-inner-icon="mdiMagnify"
          full-width
          solo
          dense
          background-color="#FAFAFA"
        />

        <SearchResults :keyword="keyword" />
      </v-card-text>
    </v-card>
  </v-app>
</template>

<script >
import { mdiMagnify } from '@mdi/js'
import SearchResults from '@/components/SearchResults'

export default {
  components: {
    SearchResults,
  },
  data() {4
    return {
      keyword: '',
      mdiMagnify,
    }
  },
  beforeMount() {
    this.keyword = this.$route.params.keyword
  },
}
</script>

<style>
html {
  overflow: hidden;
}
</style>

The name of the page starts with an underscore means that we can get the URL parameter with the file name as the property name with the URL parameter value, so we can access the URL parameter value with the this.$route.params.keyword property.

Then in components/SearchResults.vue that we created, we add:

<template>
  <div>
    <div v-if="loading" class="my-3">
      <v-card>
        <v-card-text> Loading... </v-card-text>
      </v-card>
    </div>
    <div v-else id="scrollable" class="my-3">
      <v-card
        v-for="r of filteredSearchResultsWithHighlight"
        :key="r.id"
        class="my-3"
        :style="{
          border: highlightStatus[r.id] ? '2px solid lightblue' : undefined,
        }"
        @click="
          highlightStatus = {}
          $set(highlightStatus, r.id, !highlightStatus[r.id])
        "
      >
        <v-card-text class="d-flex pa-0 ma-0">
          <img :src="r.avatar" class="avatar" />
          <div
            class="flex-grow-1 pa-3 d-flex flex-column justify-space-between right-pane"
          >
            <div class="d-flex justify-space-between">
              <div>
                <h2 v-html="r.name"></h2>
                <p class="py-0 my-0">
                  <b v-html="r.title"></b>
                </p>
                <p class="py-0 my-0">
                  <span v-html="r.address"></span>,
                  <span v-html="r.city"></span>
                </p>
              </div>
              <div v-html="r.email"></div>
            </div>

            <div>
              <v-btn text color="#00897B">Mark as Suitable</v-btn>
            </div>
          </div>
        </v-card-text>
      </v-card>
    </div>
  </div>
</template>

<script>
import db from '@/db'

export default {
  props: {
    keyword: {
      type: String,
      default: '',
    },
  },
  data() {
    return {
      highlightStatus: {},
      filteredSearchResults: [],
      loading: false,
    }
  },
  computed: {
    filteredSearchResultsWithHighlight() {
      const { keyword } = this
      if (!Array.isArray(this.filteredSearchResults)) {
        return []
      }
      const highlighted = this.filteredSearchResults?.map((u) => {
        const highlightedEntries = Object.entries(u)?.map(([key, val]) => {
          if (key === 'avatar' || key === 'id') {
            return [key, val]
          }
          const highlightedVal = val?.replace(
            new RegExp(keyword, 'gi'),
            (match) => `<mark>${match}</mark>`
          )
          return [key, highlightedVal]
        })
        return Object.fromEntries(highlightedEntries)
      })
      return highlighted
    },
  },
  watch: {
    keyword: {
      immediate: true,
      handler() {
        this.search()
      },
    },
  },
  beforeMount() {
    this.loadData()
  },
  methods: {
    async search() {
      await this.$nextTick()
      const { keyword } = this
      if (keyword) {
        const filteredSearchResults = await db.avatars
          .filter((u) => {
            const { address, city, email, name, title } = u
            return (
              address?.toLowerCase()?.includes(keyword?.toLowerCase()) ||
              city?.toLowerCase()?.includes(keyword?.toLowerCase()) ||
              email?.toLowerCase()?.includes(keyword?.toLowerCase()) ||
              name?.toLowerCase()?.includes(keyword?.toLowerCase()) ||
              title?.toLowerCase()?.includes(keyword?.toLowerCase())
            )
          })
          .limit(10)
          .toArray()
        this.filteredSearchResults = filteredSearchResults
      } else {
        this.filteredSearchResults = await db.avatars
          ?.toCollection()
          ?.limit(10)
          .toArray()
      }
    },
    loadData() {
      this.loading = true
      const worker = this.$worker.createWorker()
      worker.onmessage = () => {
        this.search()
        this.loading = false
      }
      worker.postMessage('load')
    },
  },
}
</script>

<style>
.avatar {
  background: #bdbdbd;
  width: 150px;
}

.right-pane {
  background: #fafafa;
}

mark {
  background: yellow;
}

#scrollable {
  height: calc(100vh - 100px);
  overflow-y: auto;
}
</style>

In the loadData method. we call this.$worker.createWorker to create the worker that we injected.

this.$worker is available since the inject-ww.js script is run when the app is loaded.

We set worker.onmessage to a function so that we recent messages from the worker when postMessage in the onmessage function of the worker is called.

Once we received a message from the web workwer, we call the this.search method to do the filtering according to the keyword value.

And we call worker.postMessage with anything so that the worker’s onmessage function in the worker will start running.

Now when we type in something into the text box, we see results displayed in the cards.

We should be able to load large amounts of data in the web worker without hanging the browser since it’s run in the background.

Conclusion

To run background tasks in a Nuxt app with web workers, we can add the Webpack’s worker-loader package into our Nuxt project.

Also, we’ve to make sure that web workers are only loaded on client side.

We’ll make a project that loads a large JSON file and searches it.

Categories
Vue

How to Create Web Components with Vue.js

Component-based architecture is the main architecture for front end development today. The World Wide Web Consortium (W3C) has caught up to the present by creating the web components API. It lets developers build custom elements that can be embedded in web pages. The elements can be reused and nested anywhere, allowing for code reuse in any pages or apps.

The custom elements are nested in the shadow DOM, which is rendered separately from the main DOM of a document. This means that they are completely isolated from other parts of the page or app, eliminating the chance of conflict with other parts,

There are also template and slot elements that aren’t rendered on the page, allowing you to reused the things inside in any place.

To create web components without using any framework, you have to register your element by calling CustomElementRegistry.define() and pass in the name of the element you want to define. Then you have to attach the shadow DOM of your custom element by calling Element.attachShawdow() so that your element will be displayed on your page.

This doesn’t include writing the code that you want for your custom elements, which will involve manipulating the shadow DOM of your element. It is going to be frustrating and error-prone if you want to build a complex element.

Vue.js abstracts away the tough parts by letting you build your code into a web component. You write code by importing and including the components in your Vue components instead of globally, and then you can run commands to build your code into one or more web components and test it.

We build the code into a web component with Vue CLI by running:

npm run build -- --target wc --inline-vue --name custom-element-name

The --inline-vue flag includes a copy of view in the built code, --target wc builds the code into a web component, and --name is the name of your element.

In this article, we will build a weather widget web component that displays the weather from the OpenWeatherMap API. We will add a search to let users look up the current weather and forecast from the API.

We will use Vue.js to build the web component. To begin building it, we start with creating the project with Vue CLI. Run npx @vue/cli create weather-widget to create the project. In the wizard, select Babel, SCSS and Vuex.

The OpenWeatherMap API is available at https://openweathermap.org/api. You can register for an API key here. Once you got an API key, create an .env file in the root folder and add VUE_APP_APIKEY as the key and the API key as the value.

Next, we install some packages that we need for building the web component. We need Axios for making HTTP requests, BootstrapVue for styling, and Vee-Validate for form validation. To install them, we run npm i axios bootstrap-vue vee-validate to install them.

With all the packages installed we can start writing our code. Create CurrentWeather.vue in the components folder and add:

<template>
  <div>
    <br />
    <b-list-group v-if="weather.main">
      <b-list-group-item>Current Temparature: {{weather.main.temp - 273.15}} C</b-list-group-item>
      <b-list-group-item>High: {{weather.main.temp_max - 273.15}} C</b-list-group-item>
      <b-list-group-item>Low: {{weather.main.temp_min - 273.15}} C</b-list-group-item>
      <b-list-group-item>Pressure: {{weather.main.pressure }}mb</b-list-group-item>
      <b-list-group-item>Humidity: {{weather.main.humidity }}%</b-list-group-item>
    </b-list-group>
  </div>
</template>

<script>
import { requestsMixin } from "@/mixins/requestsMixin";
import store from "../store";
import { BListGroup, BListGroupItem } from "bootstrap-vue";
import 'bootstrap/dist/css/bootstrap.css'
import 'bootstrap-vue/dist/bootstrap-vue.css'

export default {
  store,
  name: "CurrentWeather",
  mounted() {},
  mixins: [requestsMixin],
  components: {
    BListGroup,
    BListGroupItem
  },
  computed: {
    keyword() {
      return this.$store.state.keyword;
    }
  },
  data() {
    return {
      weather: {}
    };
  },
  watch: {
    async keyword(val) {
      const response = await this.searchWeather(val);
      this.weather = response.data;
    }
  }
};
</script>

<style scoped>
p {
  font-size: 20px;
}
</style>

This component displays the current weather from the OpenWeatherMap API as the keyword from the Vuex store is updated. We will create the Vuex store later. The this.searchWeather function is from the requestsMixin , which is a Vue mixin that we will create. The computed block gets the keyword from the store via this.$store.state.keyword and return the latest value.

Note that we’re importing all the BootstrapVue components individually here. This is because we aren’t building an app. main.js in our project will not be run, so we cannot register components globally by calling Vue.use . Also, we have to import the store here, so that we have access to the Vuex store in the component.

Next, create Forecast.vue in the same folder and add:

<template>
  <div>
    <br />
    <b-list-group v-for="(l, i) of forecast.list" :key="i">
      <b-list-group-item>
        <b>Date: {{l.dt_txt}}</b>
      </b-list-group-item>
      <b-list-group-item>Temperature: {{l.main.temp - 273.15}} C</b-list-group-item>
      <b-list-group-item>High: {{l.main.temp_max - 273.15}} C</b-list-group-item>
      <b-list-group-item>Low: {{l.main.temp_min }}mb</b-list-group-item>
      <b-list-group-item>Pressure: {{l.main.pressure }}mb</b-list-group-item>
    </b-list-group>
  </div>
</template>

<script>
import { requestsMixin } from "@/mixins/requestsMixin";
import store from "../store";
import { BListGroup, BListGroupItem } from "bootstrap-vue";
import 'bootstrap/dist/css/bootstrap.css'
import 'bootstrap-vue/dist/bootstrap-vue.css'

export default {
  store,
  name: "Forecast",
  mixins: [requestsMixin],
  components: {
    BListGroup,
    BListGroupItem
  },
  computed: {
    keyword() {
      return this.$store.state.keyword;
    }
  },
  data() {
    return {
      forecast: []
    };
  },
  watch: {
    async keyword(val) {
      const response = await this.searchForecast(val);
      this.forecast = response.data;
    }
  }
};
</script>

<style scoped>
p {
  font-size: 20px;
}
</style>

It’s very similar to CurrentWeather.vue . The only difference is that we are getting the current weather instead of the weather forecast.

Next, we create a mixins folder in the src folder and add:

const APIURL = "[http://api.openweathermap.org](http://api.openweathermap.org)";
const axios = require("axios");

export const requestsMixin = {
  methods: {
    searchWeather(loc) {
      return axios.get(
        `${APIURL}/data/2.5/weather?q=${loc}&appid=${process.env.VUE_APP_APIKEY}`
      );
    },

searchForecast(loc) {
      return axios.get(
        `${APIURL}/data/2.5/forecast?q=${loc}&appid=${process.env.VUE_APP_APIKEY}`
      );
    }
  }
};

These functions are for getting the current weather and the forecast respectively from the OpenWeatherMap API. process.env.VUE_APP_APIKEY is obtained from our .env file that we created earlier.

Next in App.vue , we replace the existing code with:

<template>
  <div>
    <b-navbar toggleable="lg" type="dark" variant="info">
      <b-navbar-brand href="#">Weather App</b-navbar-brand>
    </b-navbar>
    <div class="page">
      <ValidationObserver ref="observer" v-slot="{ invalid }">
        <b-form @submit.prevent="onSubmit" novalidate>
          <b-form-group label="Keyword" label-for="keyword">
            <ValidationProvider name="keyword" rules="required" v-slot="{ errors }">
              <b-form-input
                :state="errors.length == 0"
                v-model="form.keyword"
                type="text"
                required
                placeholder="Keyword"
                name="keyword"
              ></b-form-input>
              <b-form-invalid-feedback :state="errors.length == 0">Keyword is required</b-form-invalid-feedback>
            </ValidationProvider>
          </b-form-group>

          <b-button type="submit" variant="primary">Search</b-button>
        </b-form>
      </ValidationObserver>

      <br />

      <b-tabs>
        <b-tab title="Current Weather">
          <CurrentWeather />
        </b-tab>
        <b-tab title="Forecast">
          <Forecast />
        </b-tab>
      </b-tabs>
    </div>
  </div>
</template>

<script>
import CurrentWeather from "@/components/CurrentWeather.vue";
import Forecast from "@/components/Forecast.vue";
import store from "./store";
import {
  BTabs,
  BTab,
  BButton,
  BForm,
  BFormGroup,
  BFormInvalidFeedback,
  BNavbar,
  BNavbarBrand,
  BFormInput
} from "bootstrap-vue";
import { ValidationProvider, extend, ValidationObserver } from "vee-validate";
import { required } from "vee-validate/dist/rules";
extend("required", required);

export default {
  store,
  name: "App",
  components: {
    CurrentWeather,
    Forecast,
    ValidationProvider,
    ValidationObserver,
    BTabs,
    BTab,
    BButton,
    BForm,
    BFormGroup,
    BFormInvalidFeedback,
    BNavbar,
    BNavbarBrand,
    BFormInput
  },
  data() {
    return {
      form: {}
    };
  },
  methods: {
    async onSubmit() {
      const isValid = await this.$refs.observer.validate();
      if (!isValid) {
        return;
      }
      localStorage.setItem("keyword", this.form.keyword);
      this.$store.commit("setKeyword", this.form.keyword);
    }
  },
  beforeMount() {
    this.form = { keyword: localStorage.getItem("keyword") || "" };
  },
  mounted() {
    this.$store.commit("setKeyword", this.form.keyword);
  }
};
</script>

<style lang="scss">
@import "./../node_modules/bootstrap/dist/css/bootstrap.css";
@import "./../node_modules/bootstrap-vue/dist/bootstrap-vue.css";
.page {
  padding: 20px;
}
</style>

We add the BootstrapVue b-navbar here to add a top bar to show the extension’s name. Below that, we added the form for searching the weather info. Form validation is done by wrapping the form in the ValidationObserver component and wrapping the input in the ValidationProvider component. We provide the rule for validation in the rules prop of ValidationProvider . The rules will be added in main.js later.

The error messages are displayed in the b-form-invalid-feedback component. We get the errors from the scoped slot in ValidationProvider . It’s where we get the errors object from.

When the user submits the number, the onSubmit function is called. This is where the ValidationObserver becomes useful as it provides us with the this.$refs.observer.validate() function to check for form validity.

If isValid resolves to true , then we set the keyword in local storage, and also in the Vuex store by running this.$store.commit(“setKeyword”, this.form.keyword); .

In the beforeMount hook, we set the keyword so that it will be populated when the extension first loads if a keyword was set in local storage. In the mounted hook, we set the keyword in the Vuex store so that the tabs will get the keyword to trigger the search for the weather data.

Like in the previous components, we import and register all the components and the Vuex store in this component, so that we can use the BootstrapVue components here. We also called Vee-Validate’s extend function so that we can use its required form validation rule for checking the input.

In style section of this file, we import the BootstrapVue styles, so that they can be accessed in this and the child components. We also add the page class so that we can add some padding to the page.

Then in store.js , we replace the existing code with:

import Vue from "vue";
import Vuex from "vuex";

Vue.use(Vuex);

export default new Vuex.Store({
  state: {
    keyword: ""
  },
  mutations: {
    setKeyword(state, payload) {
      state.keyword = payload;
    }
  },
  actions: {}
});

to add the Vuex store that we referenced in the components. We have the keyword state for storing the search keyword in the store, and the setKeyword mutation function so that we can set the keyword in our components.

Finally, in package.json , we add 2 scripts to the scripts section of the file:

"wc-build": "npm run build -- --target wc --inline-vue --name weather-widget",

"wc-test": "cd dist && live-server --port=8080 --entry-file=./demo.html"

The wc-build script builds our code into a web component as we described before, and the wc-test runs a local web server so that we can see what the web component looks like when it’s included in a web page. We use the live-server NPM package for serving the file. The --entry-file option specifies that we server demo.html as the home page, which we get when we run npm run wc-build .

If we run npm run wc-build and npm run wc-test , we get:

As you can see, we get the web component’s shadow DOM rendered in the browser and in the developer console.

We created a web component with less effort than using plain JavaScript, especially for something complex enough to have nesting and interactions.