HtmlExample.git

			@@ -1,38 +1,93 @@
			<html>
			<head>
			<title>Promise</title>
			<title>Promise</title>
			<script type='text/javascript'>
			var ok = true;
			function successCallBack(){
			console.log("成功");
			//1.链式回调通过多次调用 then() 可以添加多个回调函数，它们会按照插入顺序进行执行。
			const doSomething = () => new Promise((resolve,reject)=>{setTimeout(() => {
			console.log("在setTimeout中做了些事");
			reject();
			}, 10);});
			const successCallBack = () => {
			console.log("成功的回调");
			};
			function failureCallBack(){
			console.log("失败");
			};
			function successCallBack1(){
			console.log("成功1");
			};
			function failureCallBack1(){
			console.log("失败1");
			};
			const successCallBack1 = () => new Promise((resolve,reject)=>{setTimeout(() => {
			console.log("成功的回调1");
			reject();
			}, 10);});
			const failureCallBack = () => {
			console.log("失败的回调");
			};
			//返回Promise对象，输出"在setTimeout中做了些事"文本，但是没有执行reject回调。
			const promise = doSomething();
			//执行promise对象的reject回调failureCallBack()，输出“失败的回调”文本，返回promise2对象，由于failureCallBack()方法中没有手动创建Promise所以这里返回的是默认的Promise对象
			const promise2 = promise.then(successCallBack,failureCallBack);
			//执行promise2默认回调successCallBack(),返回默认对象promise3
			const promise3 = promise2.then(successCallBack,failureCallBack);
			//简写
			doSomething().then(successCallBack,failureCallBack).then(successCallBack,failureCallBack);
			//successCallBack1返回用户自己创建的Promise，并且指定了回调函数
			doSomething().then(successCallBack,failureCallBack).then(successCallBack,failureCallBack).then(successCallBack1,failureCallBack).then(successCallBack,failureCallBack);

			const wait = ()=> new Promise((resolve,reject)=> {
			setTimeout(() => {
			console.log('setTimeout1执行完毕');
			//.catch()、finally()
			const promise4 = new Promise((resolve,reject)=>{setTimeout(() => {
			console.log("promise4：在setTimeout中做了些事");
			console.log("选择路径[A]");
			resolve("路径：A0");
			//reject("路径：A1");
			},10)})
			.then(resolvePara => new Promise((resolve2,reject2) => {
			console.log("promise4 then1：成功的回调");
			throw new Error("是错误哦");
			console.log(resolvePara);
			console.log("选择路径[B]");
			resolve2(resolvePara + " B0");
			//reject2(resolvePara + " B1");
			}), rejectPara => new Promise((resolve2,reject2) => {
			console.log("promise4 then1：失败的回调");
			console.log(rejectPara);
			console.log("选择路径[B]");
			resolve2(resolvePara + " B0");
			//reject2(resolvePara + " B1");
			}))
			.then(resolvePara => new Promise((resolve3,reject3) => {
			console.log("promise4 then1 then2：成功的回调");
			console.log(resolvePara);
			console.log("选择路径[C]");
			resolve3(resolvePara + " C0");
			//reject3(resolvePara + " C1");
			}), rejectPara => new Promise((resolve3,reject3) => {
			console.log("promise4 then1 then2：失败的回调");
			console.log(rejectPara);
			console.log("选择路径[C]");
			resolve3(resolvePara + " C0");
			//reject3(resolvePara + " C1");
			}))
			.catch(rejectPara => {
			console.log("promise4 catch：异常的回调");
			console.log(rejectPara);
			})
			.finally(() => {
			console.log("promise4 finally：执行完毕");
			})
			//通常，一遇到异常抛出，浏览器就会顺着 Promise 链寻找下一个 onRejected 失败回调函数或者由 .catch() 指定的回调函数。
			//finally不管成功失败都会执行内部代码，不接受参数。


			//2.在本轮事件循环运行完成之前，回调函数是不会被调用的。
			console.log("在本轮事件循环运行完成之前，回调函数是不会被调用的，你看我是最先执行的");
			//3.即使异步操作已经完成（成功或失败），在这之后通过 then() 添加的回调函数也会被调用。
			const promise5 = new Promise((resolve)=>{
			setTimeout(()=>{
			console.log("promise5 执行的异步操作");
			resolve();
			}, 0);
			});

			//调用报错，wait2返回的是setTimeout方法。
			const wait1 = ()=> setTimeout(() => {
			console.log('setTimeout2执行完毕');
			return new Promise((resolve,reject)=> {
			resolve();
			},10);
			});
			setTimeout(()=>{
			promise5.then(() => {
			console.log("promise5 即使异步操作已经完成（成功或失败），在这之后通过 then() 添加的回调函数也会被调用");
			});
			}, 0);


			var use = wait().then(successCallBack,failureCallBack).then(successCallBack1,failureCallBack1);
			},1000);
			//3.
			</script>
			</head>
			<body>