Category: Vue Answers

Sometimes, we want to fix window is not defined in Vue.js.

In this article, we’ll look at how to fix window is not defined in Vue.js.

How to fix window is not defined in Vue.js?

To fix window is not defined in Vue.js, we should add the browser property and set it to true in the ESLint config.

For instance, we write

module.exports = {
  //...
  env: {
    browser: true,
    node: true,
  },
  //...
};

to add the env.browser property and set it to true so ESLint will stop throwing the window is not defined error.

Conclusion

To fix window is not defined in Vue.js, we should add the browser property and set it to true in the ESLint config.

Sometimes, we want to watch the change of an element value with Vue.js.

In this article, we’ll look at how to watch the change of an element value with Vue.js.

How to watch the change of an element value with Vue.js?

To watch the change of an element value with Vue.js, we can add a watcher.

For instance, we write

<script>
//...
export default {
  //...
  watch: {
    myValue(val, oldVal) {
      if (val < 50) {
        this.message = "value too low!";
      } else {
        this.message = "value is ok";
      }
    },
  },
  //...
};
</script>

to watch the myValue reactive property for changes.

We get its latest value from val and its previous value from oldVal.

And then we can do whatever we want in the watcher method according to the values.

Conclusion

To watch the change of an element value with Vue.js, we can add a watcher.

Sometimes, we want to change object in array and trigger reactivity with Vue.js

In this article, we’ll look at how to change object in array and trigger reactivity with Vue.js.

How to change object in array and trigger reactivity with Vue.js?

To change object in array and trigger reactivity with Vue.js, we can use the this.$set method.

For instance, we write

<script>
//...
export default {
  //...
  methods: {
    update(index) {
      this.$set(this.arr, index, { ...this.arr[index], foo: "bar" });
    },
  },
  //...
};
</script>

to call this.$set with the this.arr array we want to update, the index of the item we want to update, and the object we want to update the object at the index to.

Calling this.$set will trigger Vue.js to notice the changes in the object in the array that’s changed and re-render the component.

Conclusion

To change object in array and trigger reactivity with Vue.js, we can use the this.$set method.

Sometimes, we want to hide a div with Vue.js.

In this article, we’ll look at how to hide a div with Vue.js.

How to hide a div with Vue.js?

To hide a div with Vue.js, we can use the v-if directive.

For instance, we write

<template>
  <div>
    <div v-if="seen" id="hide">
      <p>hide me</p>
    </div>
  </div>
</template>

to show the div only if seen if true by adding v-if="seen" to the div.

Conclusion

To hide a div with Vue.js, we can use the v-if directive.

Sometimes, we want to access $route.params in Vue.js.

In this article, we’ll look at how to access $route.params in Vue.js.

How to access $route.params in Vue.js?

To access $route.params in Vue.js, we access it from this in the options API.

In the composition API, we use the useRoute hook.

For instance, we write

<script>
//...
export default {
  //...
  methods: {
    get() {
      console.log(this.$route.params.id);
    },
  },
  //...
};
</script>

to get the value of the id route parameter with this.$route.params.id with the options API.

With the composition API, we use the useRoute hook by writing

<script>
import { useRoute } from "vue-router";
//...
export default {
  //...
  setup() {
    const route = useRoute();
    const id = route.params.id;
  },
  //...
};
</script>

We call useRoute to return the route object and then we get the value of the id route parameter with route.params.id.

Conclusion

To access $route.params in Vue.js, we access it from this in the options API.

In the composition API, we use the useRoute hook.