~~~
class State {
constructor(color) {
this.color = color
}
handle(context) {
console.log(`turn to ${this.color} light`)
context.setState(this)
}
}
class Context {
constructor() {
this.state = null
}
setState(state) {
this.state = state
}
getState() {
return this.state
}
}
// 測試代碼
let context = new Context()
let green = new State('green')
let yellow = new State('yellow')
let red = new State('red')
// 綠燈亮了
green.handle(context)
console.log(context.getState())
// 黃燈亮了
yellow.handle(context)
console.log(context.getState())
// 紅燈亮了
red.handle(context)
console.log(context.getState())
~~~
~~~
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<p>有限狀態機</p>
<button id="btn"></button>
<script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.min.js"></script>
<script src="./03-javascript-state-machine.js"></script>
<script>
// 狀態機模型
var fsm = new StateMachine({
init: '收藏', // 初始狀態，待收藏
transitions: [
{
name: 'doStore',
from: '收藏',
to: '取消收藏'
},
{
name: 'deleteStore',
from: '取消收藏',
to: '收藏'
}
],
methods: {
// 執行收藏
onDoStore: function () {
alert('收藏成功')
updateText()
},
// 取消收藏
onDeleteStore: function () {
alert('已取消收藏')
updateText()
}
}
})
var $btn = $('#btn')
// 點擊事件
$btn.click(function () {
if (fsm.is('收藏')) {
fsm.doStore(1)
} else {
fsm.deleteStore()
}
})
// 更新文案
function updateText() {
$btn.text(fsm.state)
}
// 初始化文案
updateText()
</script>
</body>
</html>
~~~
~~~
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.min.js"></script>
<script src="./03-javascript-state-machine.js"></script>
<script>
// 模型
var fsm = new StateMachine({
init: 'pending',
transitions: [
{
name: 'resolve',
from: 'pending',
to: 'fullfilled'
},
{
name: 'reject',
from: 'pending',
to: 'rejected'
}
],
methods: {
// 成功
onResolve: function (state, data) {
// 參數：state - 當前狀態示例; data - fsm.resolve(xxx) 執行時傳遞過來的參數
data.successList.forEach(fn => fn())
},
// 失敗
onReject: function (state, data) {
// 參數：state - 當前狀態示例; data - fsm.reject(xxx) 執行時傳遞過來的參數
data.failList.forEach(fn => fn())
}
}
})
// 定義 Promise
class MyPromise {
constructor(fn) {
this.successList = []
this.failList = []
fn(() => {
// resolve 函數
fsm.resolve(this)
}, () => {
// reject 函數
fsm.reject(this)
})
}
then(successFn, failFn) {
this.successList.push(successFn)
this.failList.push(failFn)
}
}
// 測試代碼
function loadImg(src) {
const promise = new MyPromise(function (resolve, reject) {
var img = document.createElement('img')
img.onload = function () {
resolve(img)
}
img.onerror = function () {
reject()
}
img.src = src
})
return promise
}
var src = 'http://www.imooc.com/static/img/index/logo_new.png'
var result = loadImg(src)
console.log(result)
result.then(function (img) {
console.log('success 1')
}, function () {
console.log('failed 1')
})
result.then(function (img) {
console.log('success 2')
}, function () {
console.log('failed 2')
})
</script>
</body>
</html>
~~~
