码农教程 - 一技在手,衣食无忧! tools

目录

Vue Template Refs

❮ Previous Next ❯

Vue Template Refs are used to refer to specific DOM elements.

When the ref attribute is set on an HTML tag, the resulting DOM element is added to the $refs object.

We can use the ref attribute and the $refs object in Vue as an alternative to methods in plain JavaScript like getElementById() or querySelector().

The 'ref' Attribute and The '$refs' Object

HTML tags with the ref attribute will be added to the $refs object and can be reached later from inside the <script> tag.

Example

The text inside a <p> element is changed.

App.vue:

<template>
  <h1>Example</h1>
  <p>Click the button to put "Hello!" as the text in the green p element.</p>
  <button @click="changeVal">Change Text</button>
  <p ref="pEl">This is the initial text</p>
</template>

<script>
  export default {
    methods: {
      changeVal() {
        this.$refs.pEl.innerHTML = "Hello!";
      }
    }
  }
</script>
Run Example »

Below is another example where the $refs object is used to copy the value of one tag into another tag.

Example

The text from the first <p> tag is copied into the second <p> tag.

App.vue:

<template>
  <h1>Example</h1>
  <p ref="p1">Click the button to copy this text into the paragraph below.</p>
  <button @click="transferText">Transfer text</button>
  <p ref="p2">...</p>
</template>

<script>
  export default {
    methods: {
      transferText() { 
        this.$refs.p2.innerHTML = this.$refs.p1.innerHTML;
      }
    }
  };
</script>
Run Example »

Get The Input Value from '$refs'

We can go further into an HTML element added to the $refs object to access any property we want.

Example

A <p> element gets the same content as what's being written in the input field.

App.vue:

<template>
  <h1>Example</h1>
  <p>Start writing inside the input element, and the text will be copied into the last paragraph by the use of the '$refs' object.</p>
  <input ref="inputEl" @input="getRefs" placeholder="Write something..">
  <p ref="pEl"></p>
</template>

<script>
  export default {
    methods: {
      getRefs() { 
        this.$refs.pEl.innerHTML = this.$refs.inputEl.value;
      }
    }
  };
</script>
Run Example »

'ref' with v-for

HTML elements created with v-for, with the ref attribute, will be added to the $refs object as an array.

Example

The button reveals the the third list element stored as an array element inside the $refs object.

App.vue:

<template>
  <h1>Example</h1>
  <p>Click the button to reveal the 3rd list element stored as an array element in the $refs object.</p>
  <button @click="getValue">Get the 3rd list element</button><br>
  <ul>
    <li v-for="x in liTexts" ref="liEl">{{ x }}</li>
  </ul>
  <pre>{{ thirdEl }}</pre>
</template>

<script>
  export default {
    data() {
      return {
        thirdEl: ' ',
        liTexts: ['Apple','Banana','Kiwi','Tomato','Lichi']
      }
    },
    methods: {
      getValue() { 
        this.thirdEl = this.$refs.liEl[2].innerHTML;
        console.log("this.$refs.liEl = ",this.$refs.liEl);
      }
    }
  };
</script>

<style>
pre {
  background-color: lightgreen;
  display: inline-block;
}
</style>
Run Example »

Vue Exercises

Test Yourself With Exercises

Exercise:

Refs are used to refer to specific DOM elements.

Supply the missing code so that 'Hello World' is displayed in the second <p> tag when the application is mounted.

<template>
  <p>This is just some text.</p>
  <p >This is the initial text</p>
</template>

<script>
  export default {
    mounted() {
      this..pEl.innerHTML = "Hello World!";
    }
  };
</script>

Start the Exercise


❮ Previous Next ❯