How to use add in vue

Vue.js is a popular open source JavaScript framework for building interactive web user interfaces. It is lightweight, progressive, easy to learn and use.

Vue.js provides many APIs for manipulating objects and arrays, including the add() method. The add() method is used to add new elements to the array. It can add one or more elements to the end of the array. This article will introduce in detail the usage and examples of the add() method of Vue.js.

The add() method in Vue.js

In Vue.js, we can use the add() method to add new elements to an array. The add() method is a method on the Array prototype chain. Its usage is as follows:

Vue.set(array, indexOfElement, newValue)

Among them, array is the original array to add elements; indexOfElement is the position of the element to be added; newValue is the new value to be added. element.

A few points about the add() method:

• The add() method can only add new elements to the responsive array, and cannot use the push() method directly, because push () method does not support reactivity.
• Since the add() method adds new elements to the responsive array, the Vue.set() method must be used to trigger view updates. When using the Vue.set() method, Vue.js will automatically detect whether the array is reactive. Using Vue.set() in a non-reactive array will result in a warning.
• If we want to add multiple elements to the array, we can call the add() method multiple times, or use the concat() method to merge the two arrays.

The following is an example of adding new elements to an array through the add() method:

<template>
  <div>
    <ul>
      <li v-for="(item, index) in items" :key="index">
        {{ item }}
      </li>
    </ul>
    <button @click="addItem">添加新项</button>
  </div>
</template>

<script>
export default {
  data() {
    return {
      items: ["苹果", "桃子", "李子"],
    };
  },
  methods: {
    addItem() {
      //将橙子添加到数组的末尾
      Vue.set(this.items, this.items.length, "橙子");
    },
  },
};
</script>

In the above example, we define an array items, and then addItem( ) method calls the Vue.set() method to add a new element "orange" to the array. We used this.items.length as the position to add the element to so that when adding a new element it will automatically be added to the end of the array.

We can click the "Add New Item" button to add new elements to the array. Every time a new element is added, the array in the page is updated and displays the newly added element.

Summary

The add() method of Vue.js can add elements to a specified position in a responsive array. It is one of the APIs provided by Vue.js. We can use the add() method to add new elements to the array. When adding elements, the Vue.set() method must be used to trigger page updates. Using the add() method to add elements is very convenient and can help us better handle array operations.

At the same time, in actual development, we can also use other APIs provided by Vue.js to operate arrays, such as slice(), splice(), shift(), etc. These APIs can meet our various needs and allow us to develop more efficiently.

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