This time I will show you how to use ES6 classes to imitate Vue to write a two-way binding. Use ES6 classes to imitate Vue to write a two-way binding. What are the precautions? What are the practical cases below? Let’s take a look.
The final effect is as follows:
Constructor (constructor)
Constructs a TinyVue object, including basic el, data, methods
class TinyVue{ constructor({el, data, methods}){ this.$data = data this.$el = document.querySelector(el) this.$methods = methods // 初始化 this._compile() this._updater() this._watcher() } }
Compiler(compile)
Used to parse click events of v-model and elements bound to input boxes and drop-down boxes@ click.
First create a function to load events:
// el为元素tagName,attr为元素属性(v-model,@click) _initEvents(el, attr, callBack) { this.$el.querySelectorAll(el).forEach(i => { if(i.hasAttribute(attr)) { let key = i.getAttribute(attr) callBack(i, key) } }) }
Load input box event
this._initEvents('input, textarea', 'v-model', (i, key) => { i.addEventListener('input', () => { Object.assign(this.$data, {[key]: i.value}) }) })
Load selection box event
this._initEvents('select', 'v-model', (i, key) => { i.addEventListener('change', () => Object.assign(this.$data, {[key]: i.options[i.options.selectedIndex].value})) })
Load click Event
The click event corresponds to the event in methods
this._initEvents('*', '@click', (i, key) => { i.addEventListener('click', () => this.$methods[key].bind(this.$data)()) })
View updater(updater)
In the same way, first create a public function to handle different The view in the element includes the value of input and textarea, the selection value of select, and the innerHTML of p
_initView(el, attr, callBack) { this.$el.querySelectorAll(el, attr, callBack).forEach(i => { if(i.hasAttribute(attr)) { let key = i.getAttribute(attr), data = this.$data[key] callBack(i, key, data) } }) }
Update the input box view
this._initView('input, textarea', 'v-model', (i, key, data) => { i.value = data })
Update the selection box view
this._initView('select', 'v-model', (i, key, data) => { i.querySelectorAll('option').forEach(v => { if(v.value == data) v.setAttribute('selected', true) else v.removeAttribute('selected') }) })
Update innerHTML
The implementation method here is a bit low. I only think of regular replacement {{text}}
let regExpInner = /\{{ *([\w_\-]+) *\}}/g this.$el.querySelectorAll("*").forEach(i => { let replaceList = i.innerHTML.match(regExpInner) || (i.hasAttribute('vueID') && i.getAttribute('vueID').match(regExpInner)) if(replaceList) { if(!i.hasAttribute('vueID')) { i.setAttribute('vueID', i.innerHTML) } i.innerHTML = i.getAttribute('vueID') replaceList.forEach(v => { let key = v.slice(2, v.length - 2) i.innerHTML = i.innerHTML.replace(v, this.$data[key]) }) } })
Listener (watcher)
Update after data changes View
<p id="app"> <input type="text" v-model="text1"><br> <input type="text" v-model="text2"><br> <textarea type="text" v-model="text3"></textarea><br> <button @click="add">加一</button> <h1>您输入的是:{{text1}}+{{text2}}+{{text3}}</h1> <select v-model="select"> <option value="volvo">Volvo</option> <option value="saab">Saab</option> </select> <select v-model="select"> <option value="volvo">Volvo</option> <option value="saab">Saab</option> </select> <h1>您选择了:{{select}}</h1> </p> <script src="./TinyVue.js"></script> <script> let app = new TinyVue({ el: '#app', data: { text1: 123, text2: 456, text3: '文本框', select: 'saab' }, methods: { add() { this.text1 ++ this.text2 ++ } } }) </script>
TinyVue all code
class TinyVue{ constructor({el, data, methods}){ this.$data = data this.$el = document.querySelector(el) this.$methods = methods this._compile() this._updater() this._watcher() } _watcher(data = this.$data) { let that = this Object.keys(data).forEach(i => { let value = data[i] Object.defineProperty(data, i, { enumerable: true, configurable: true, get: function () { return value; }, set: function (newVal) { if (value !== newVal) { value = newVal; that._updater() } } }) }) } _initEvents(el, attr, callBack) { this.$el.querySelectorAll(el).forEach(i => { if(i.hasAttribute(attr)) { let key = i.getAttribute(attr) callBack(i, key) } }) } _initView(el, attr, callBack) { this.$el.querySelectorAll(el, attr, callBack).forEach(i => { if(i.hasAttribute(attr)) { let key = i.getAttribute(attr), data = this.$data[key] callBack(i, key, data) } }) } _updater() { this._initView('input, textarea', 'v-model', (i, key, data) => { i.value = data }) this._initView('select', 'v-model', (i, key, data) => { i.querySelectorAll('option').forEach(v => { if(v.value == data) v.setAttribute('selected', true) else v.removeAttribute('selected') }) }) let regExpInner = /\{{ *([\w_\-]+) *\}}/g this.$el.querySelectorAll("*").forEach(i => { let replaceList = i.innerHTML.match(regExpInner) || (i.hasAttribute('vueID') && i.getAttribute('vueID').match(regExpInner)) if(replaceList) { if(!i.hasAttribute('vueID')) { i.setAttribute('vueID', i.innerHTML) } i.innerHTML = i.getAttribute('vueID') replaceList.forEach(v => { let key = v.slice(2, v.length - 2) i.innerHTML = i.innerHTML.replace(v, this.$data[key]) }) } }) } _compile() { this._initEvents('*', '@click', (i, key) => { i.addEventListener('click', () => this.$methods[key].bind(this.$data)()) }) this._initEvents('input, textarea', 'v-model', (i, key) => { i.addEventListener('input', () => { Object.assign(this.$data, {[key]: i.value}) }) }) this._initEvents('select', 'v-model', (i, key) => { i.addEventListener('change', () => Object.assign(this.$data, {[key]: i.options[i.options.selectedIndex].value})) }) } }
I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!
Recommended reading:
How to use Vue to implement a countdown button
How to use Vue to write a two-way data binding
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