Add Basic Directives and Custom Directives

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This tutorial I will discuss a feature of framework vuejs, that is directives. some frameworks like Angular also use this feature, we will learn how to use it in vuejs. and how to make costum directive. so just let's get started.

What Will I Learn?

• Basic directive vue.js
• Costume directive

Requirements

• Install nodejs
• Install vue-cli
• Basic javascript es6

Difficulty

• Basic

Basic directive vue.js

I have made a simple component is directive.vue

<template>
  <div class="second-child">
     <h3>Built-in Directives Vuejs</h3>
  </div>
</template>
<script>
export default {
  data () {
    return {
    }
  },
}
</script>

<style scoped>
.second-child{
    margin: 0 auto;
    max-width: 600px;
    text-align: center;
}
.second-child h3{
  background: #73c000;
  color: white;
  border-radius: 10px;
}
</style>

When we install vue js, vue js already has built in directives. I will give you a few ways to use it.

v-text

v-text is useful to display the string in the form of text that will be printout in the element that we choose. I will give an example
< h4 v-text=" 'Here text from v-text' " >< /h4 >
You can add string between v-text="" , you can add as type string 'Here text from v-text'

You can add math operations in v-text. < h4 v-text="1+1">< /h4 > without string " " cause the type data is integer.

v-html

v-html is useful to print output html tags in the form of string I will give examples as follows.
< h4 v-html=" '< strong >This bold from v-html< /strong >' "> .v-html reads the html tag and prints out its results

Costume directive

Besides built-in directive, in vuejs we can costum directive according to our wishes, I tell you how to do it.

import Vue from 'vue'
import App from './App'
Vue.directive('text-highlight',{
    bind(el,binding,vnode){
el.style.backgroundColor = 'green'
    }
})
Vue.config.productionTip = false
/* eslint-disable no-new */
new Vue({
  el: '#app',
  template: '',
  components: { App }
})

Register directives

We register our custome directive globally in main.js, so we can use it in any component.

Vue.directive('text-highlight',{
    bind(el,binding,vnode){
        el.style.backgroundColor = 'green'
    }
})

Vue.directive('text-highlight',{}) : we will register and name 'text-highlight'.

bind(el,binding,vnode){} : We can bind, the element of the directive to customize the property in it. For example i take el, to change its background to green color el.style.backgroundColor = 'green'

Use Costum directive in component

You can user the Costum Directive like this .
< h5 v-text-highlight >Text background green< /h5 > : you can see the results like this. use v-text-highlight

Binding Value Costume directive

Besides you can change the style property in element, you can also bind value, or take value from costum directive and passing data. In main.js

Vue.directive('text-highlight',{
    bind(el,binding,vnode){
        el.style.backgroundColor = binding.value
    }
})

Text background red : 'red' is value we pass when register costum in main.js.

Finally we finish using the built-in directive and create our own costum directive. so much of me hopefully this tutorial gives you a picture of how directive works. thank you

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Posted on Utopian.io - Rewarding Open Source Contributors

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