Solving problems with Vue.js by effectively managing array content and reactivity issues

Question

Solving problems with Vue.js by effectively managing array content and reactivity issues

In the past, it was considered a bad practice to use the following code snippet:

array = [];

This was because if the array was referenced elsewhere, that reference wouldn't be updated correctly.

The recommended approach back then was to use array.length = 0;

However, with JavaScript being updated and the introduction of frameworks like Vue.js,

Vue does not recognize array.length = 0; for reactivity purposes. Instead, it works with array = [];

So, the question now is: Can we safely use array = []; in JavaScript, or is it still considered broken?

javascript vue.js vuejs2 vue-component v-for

Answer 1

Answer №1

When you use myArray.splice(0), it effectively clears the array content and triggers reactivity:

Vue.config.devtools = false;
Vue.config.productionTip = false;

new Vue({
  el: '#app',

  data() {
    return {
      items: ["a", "b", "c"]
    }
  },
  methods: {
    flush() {
      this.items.splice(0);
    }
  }

});

<link type="text/css" rel="stylesheet" href="//unpkg.com/bootstrap/dist/css/bootstrap.min.css" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.16/vue.js"></script>


<div id="app" class="container">

  <div v-for="i in items">{{i}}</div>

  <button @click="flush"> flush</button>
</div>

Answer 2

When you use myArray.splice(0), it effectively clears the array content and triggers reactivity:

Vue.config.devtools = false;
Vue.config.productionTip = false;

new Vue({
  el: '#app',

  data() {
    return {
      items: ["a", "b", "c"]
    }
  },
  methods: {
    flush() {
      this.items.splice(0);
    }
  }

});

<link type="text/css" rel="stylesheet" href="//unpkg.com/bootstrap/dist/css/bootstrap.min.css" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.16/vue.js"></script>


<div id="app" class="container">

  <div v-for="i in items">{{i}}</div>

  <button @click="flush"> flush</button>
</div>

Answer 3

Answer №2

Vue is unable to detect changes in an array when you directly set an item with the index, such as vm.items[indexOfItem] = newValue or modify the length of the array, like vm.items.length = newLength.

Source: Understanding Reactivity for Arrays

To clean a reactive array:

yourArray.splice(0)

Answer 4

Vue is unable to detect changes in an array when you directly set an item with the index, such as vm.items[indexOfItem] = newValue or modify the length of the array, like vm.items.length = newLength.

Source: Understanding Reactivity for Arrays

To clean a reactive array:

yourArray.splice(0)

Solving problems with Vue.js by effectively managing array content and reactivity issues

Answer №1

Answer №2

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