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Introduction to chúng tôi refs

refs in chúng tôi is defined as the referencing to make the DOM element selectable by making the key in the parent $refs and considered to be a Vue Instance property. It tells how to directly access the child functions on parent elements using this attribute and they are the most reliable attributes to reach into our templates and grab an element easily meanwhile accessing the data for that element. When a Simple DOM element is used the reference is done with that element. This Special attribute has the beauty to directly access the DOM element to fetch some data.

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Syntax:

The general syntax is given as:

How do refs work in Vue.js?

refs is not a standard HTML attributes and it is used only in Vue. When a ref attribute is added to an HTML element through Vue template, then we shall reference that element or in other case taking a child element in the Vue Instance. Generally, it is a read-only attribute and returns an Object. When an element uses ref attribute it automatically creates a link on itself inside this keyword. In other words, when Vue uses refs – say like if it is used for v-for loop, Vue dynamically creates an array of elements and if it is used in a component it refers the component instance. When we use refs in v-for, Vue automatically collects the DOM elements for iterations purpose and store them in an array.

Let’s see how refs work with simple code by accessing the DOM node.

Code:

export default { data: function () { return { query: “” }; }, mounted: function() { this.$refs[“surf”].focus(); } };

Above code explains that when we use ref attribute to input element which is accessed inside-mounted with this .$ ref [“surf”].

Examples of chúng tôi refs

Given below are the examples of chúng tôi refs:

Example #1

Showing simple example on HTML element with refs.

.html

.js

var dem = Vue.extend({ name: 'dem', data: function() { return { msg: 'Welcome' } } }) var rrr = new Vue({ el: '#rrr' })

Explanation:

Output:

Example #2

V-ref on V-for Directive

.html

<li v-for=”(obj, index) in dataObj” :key=”`function${index}`” :ref=”`${funcRef(index)}`”

new Vue({ el: "#app", data: { dataObj: [ { even: true, item: "apple" }, { even: false, item: "Mango" }, { even: true, item: "Pomegranate" }, { even: false, item: "Guava" }, { even: true, item: "Cherry" }, { even: false, item: "Tomato" }, { even: true, item: "Avacoda" } ] }, methods: { funcRef(index) { return (index % 2 === 0 ) ? 'funcItem-mod-2' :`funcItem-${index}`; }, addClassToRef(refName, className){ } }, mounted() { this.addClassToRef('expr-1', 'odd'); this.addClassToRef('expr-2', 'even'); this.addClassToRef('funcItem-mod-2','mod-2'); } });

Explanation:

Reference Access the data Object through List-items.

Output:

Example #3

Vue refs on handling conditionals

.html

chúng tôi

import Vue from 'vue' import App from './App.vue' Vue.config.productionTip = false new Vue({ }).$mount('#app')

chúng tôi

export default { name: ‘Test’, data(){ return { } }, methods: { submit(){ console.log(this.$refs) } } } p , input, button{ font-size: 22px; } input, button{ font-size: 22px; } ul { list-style-type: none; padding: 1; } li { display: inline-block; margin: 0 11px; } a { color: blanchedalmond; }

chúng tôi

import Test from ‘./components/Test.vue’ export default { name: ‘app’, components: { Test } } #app { font-family: ‘Avenir’, Helvetica, Arial, sans-serif; -webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale; text-align: center; color: yellowgreen; margin-top: 50px; }

Here in the above code, we use v-for directive so instead of returning objects, refs of array elements return a list of items. When we execute the above code in Visual Code, we get the output like this.

Output:

Example #4

Using input type

chúng tôi

export default { name: ‘Test’, data(){ return { counter: 1 } }, methods: { submit(){ this.counter++; console.log(this.$refs) } } } p , input, button{ font-size: 18px; } input, button{ font-size: 15px; } ul { list-style-type: none; padding: 1; } li { display: inline-block; margin: 0 11px; } a { color: blueviolet; }

Explanation:

In the above code, we have used a method submit() in which the refs are made to the input and the count value is incremented each time when we input something in the button.

Output:

Note: From all the above discussion, we conclude that ref() is used just for primitives.

Conclusion

This article shows how to reference HTML elements – DOM in Vue. All these are done by all the HTML elements properties like child node, attributes. We have also seen how to achieve this various example. Finally, this refs gets famous after the Vue instance has declared and most importantly they directly manipulate Child nodes.