mvvm
2019-08-06 本文已影响0人
钢笔与橡皮
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>second</title>
</head>
<body>
<div id="app" class="app">
<h2>{{name}} 's age is {{age}}</h2>
<h2>
<span>his bounty is {{money}}</span>
</h2>
<h1>{{message}}</h1>
<input v-model="message" v-on:click="sayHi" type="text">
</div>
<script>
let subjectId = 0
let observerId = 0
let currentObserver = null
class Observer {
constructor(vm, key, callback) {
this.observerId = observerId++
this.subjects = {}
this.vm = vm
this.key = key
this.callback = callback
this.value = this.getValue()
}
getValue() {
currentObserver = this
let value = this.vm[this.key]
currentObserver = null
return value
}
update() {
let oldVal = this.value
let newVal = this.getValue()
if (oldVal !== newVal) {
this.value = newVal
this.callback.bind(this)(oldVal, newVal)
}
}
subscribeTo(subject) {
if (!this.subjects[subject.subjectId]) {
subject.addObserver(this)
this.subjects[subject.subjectId] = subject
}
}
}
class Compile {
constructor(vm) {
this.vm = vm
this.node = vm.$el
this.compile()
}
compile() {
this.traverse(this.node)
}
traverse(node) {
if (node.nodeType === 1) {
this.compileNode(node)
node.childNodes.forEach(childNode => {
this.traverse(childNode)
})
} else if (node.nodeType === 3) {
this.compileText(node)
}
}
compileText(node) {
let reg = /{{(.+?)}}/g
let match
while (match = reg.exec(node.nodeValue)) {
let raw = match[0]
let key = match[1].trim()
node.nodeValue = node.nodeValue.replace(raw, this.vm[key])
new Observer(this.vm, key, function (oldValue, value) {
node.nodeValue = node.nodeValue.replace(oldValue, value)
})
}
}
compileNode(node) {
let attrs = [...node.attributes]
attrs.forEach(attr => {
if (this.isBindModel(attr.name)) {
this.bindModel(node, attr)
} else if (this.isBindEventHander(attr.name)) {
this.bindEventHander(node, attr)
}
})
}
bindModel(node, attr) {
let key = attr.value
node.value = this.vm[key]
new Observer(this.vm, key, function ({ }, newVal) {
node.value = newVal///
})
node.oninput = (e) => {
let val = e.target.value
this.vm[key] = val///setter
}
}
bindEventHander(node, attr) {
let eventType = attr.name.substr(5)
let methodName = attr.value
node.addEventListener(eventType, this.vm.$methods[methodName])
}
isBindModel(attrName) {
return attrName === 'v-model'
}
isBindEventHander(attrName) {
return attrName.indexOf('v-on') === 0
}
}
function observer(data) {
if (!data || typeof data !== 'object') { return }
for (let key in data) {
let value = data[key]
let subject = new Subject()
Object.defineProperty(data, key, {
enumerable: true,
configurable: true,
get: function () {
if (currentObserver) {
currentObserver.subscribeTo(subject)
}
return value
},
set: function (newVal) {
value = newVal
subject.notify()
}
})
if (typeof val === 'object') {
observe(val)
}
}
}
class Subject {
constructor() {
this.subjectId = subjectId++
this.observers = []
}
addObserver(observer) {
this.observers.push(observer)
}
removeObserver(observer) {
let index = this.observers.indexOf(observer)
if (index > -1) {
this.observers.splice(index, 1)
}
}
notify() {
this.observers.forEach(observer => {
observer.update()
})
}
}
class mvvm {
constructor(opts) {
this.init(opts)
observer(this.$data)
new Compile(this)
}
init(opts) {
this.$el = document.querySelector(opts.el)
this.$data = opts.data || {}
this.$methods = opts.methods || {}
for (let key in this.$data) {
Object.defineProperty(this, key, {
configurable: true,
enumerable: true,
get: () => {
return this.$data[key]
},
set: (newVal) => {
this.$data[key] = newVal
}
})
}
for (let key in this.$methods) {
this.$methods[key] = this.$methods[key].bind(this)
}
}
}
let vm = new mvvm({
el: '#app',
data: {
name: 'luffy',
age: 19,
money: 500000000,
message: `Wow,It's amazing!`
},
methods: {
sayHi() { alert(`hello,${this.name}`) }
}
})
let clock = setInterval(function () {
vm.money++
}, 1000)
//1循序渐进2搞清楚顺序,先声明容器再依次加东西3传递参数搞清楚到底想要的是什么才行4想清楚
//内在的逻辑顺序,事件发生的先后顺序,函数声明及执行的顺序非常重要.
//此处发的错误有:最后声明subjects,颠倒了渲染和劫持数据的顺序,不清楚该传入哪个参数.
//传参顺序,newval和oldval
//正则检索的逻辑不严谨导致输入的内容和计数相同时会混乱
</script>
</body>
</html>
