Vue Tips — Slots, Vue Router, and Mutations

Vue.js is a popular framework for creating front end web apps.

In this article, we’ll look at some tips for writing better Vue.js apps.

How to Pass Down Slots Inside Wrapper Component

To pass down slots in a wrapper component, we can loop through all the slots and pass them down to the child.

For instance, we can write:

<wrapper>
  <parent-table v-bind="$attrs" v-on="$listeners">

    <slot v-for="slot in Object.keys($slots)" :name="slot" :slot="slot"/>

    <template v-for="slot in Object.keys($scopedSlots)" :slot="slot" slot-scope="scope">
      <slot :name="slot" v-bind="scope"/>
    </template>

  </parent-table>
</wrapper>

We get the slots with the $slots variable.

Then we use Object.keys to get names of the slots so that we can loop through all of them and pass the name down.

Likewise, we can loop through the scoped slots with the $scopedSlots variables.

We get the keys the same way and loop through them with v-for the same way.

With Vue 2.6, the v-slot= directive is introduced to let is pass the slots down.

For instance, we can write:

<wrapper>
  <parent-table v-bind="$attrs" v-on="$listeners">
    <template v-for="(_, slot) of $scopedSlots" v-slot:[slot]="scope">
      <slot :name="slot" v-bind="scope"/>
    </template>
  </parent-table>
</wrapper>

We loop through the slot with v-for .

We get the scoped slots with the $scopedSlots variable.

slot is the slot name again.

This time, we pass it to the v-slot directive as a modifier to pass down the named slot.

scope has the scope from the scoped slot.

We use v-bind to get the scope.

And we

Alternatively, we can use render function to pass down the slots.

For instance, we can write:

render(h) {
  const children = Object.keys(this.$slots)
    .map(slot => h('template', { slot }, this.$slots[slot]))

  return h('wrapper', [
    h('parent-table', {
      attrs: this.$attrs,
      on: this.$listeners,
      scopedSlots: this.$scopedSlots,
    }, children)
  ])
}

We get the slots with the this.$slots property.

We call Object.keys to get the slot names.

And we call map on it to map the slot names to the template components.

And we pass in the slots name and the scope down,.

Then we return a wrapper component with the parent-table component with the listeners, attributes, and scoped slots and children as the children.

Get Query Parameters from a URL in Vue.js

We can get the query parameters from a URL in Vue with the this.$route.query property.

To get the query parameter foo=bar , we write:

this.$route.query.foo

and we get 'bar' as the value.

This is available assuming we’re using Vue Router in our Vue app.

If we haven’t added it, we can write:

index.html

<script src="https://unpkg.com/vue-router"></script>

index.js

const router = new VueRouter({
  mode: 'history',
  routes: [
    {
      path: '/page',
      name: 'page',
      component: PageComponent
    }
  ]
});

const vm = new Vue({
  router,
  el: '#app',
  mounted() {
    const q = this.$route.query.q;
    console.log(q)
  },
});

to get it.

We create the VueRouter instance and pass it into the object we passed into the Vue constructor.

routes has the routes.

Passing Multiple Parameters to a Mutation with Vuex

To pass multiple parameters to action with Vuex, we can pass in an object as the payload.

For instance, we can create our mutation by writing:

mutations: {
  setToken(state, { token, expiration }) {
    localStorage.setItem('token', token);
    localStorage.setItem('expiration', expiration);
  }
}

We have an object as the second parameter.

It has the token and expiration properties.

Then we can invoke the mutation by writing:

store.commit('setToken', {
  token,
  expiration,
});

We invoke the setToken mutation with the token and expiration properties in an object as the 2nd argument.

Reload Route with Vue Router

To reload a route with Vue Route, we can call the this.$router.go() method.

If it has no arguments, then it’ll reload the current route.

We can also add an unique value for the key prop to the router view:

<router-view :key="$route.fullPath"></router-view>

This way, it’ll notice when the path changes and it’ll trigger a reload of the component with new data.

Conclusion

We can reload our route with this.$router.go() .

There are many ways to pass a scope down to a child.

We can get query parameters in our component if we use Vue Router.

To pass in multiple pieces of data into a mutation, we can pass in an object with all the data we want into the mutation.