ES7的async/await

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    <title>ES7的async/await</title>    
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	<script type="text/javascript">
		// 模拟其他语言中的 sleep,实际上可以是任何异步操作
		const sleep = (timeountMS) => new Promise((resolve) => {
		 setTimeout(resolve, timeountMS);
		});
		 
		(async () => { // 声明即执行的 async 函数表达式
		 for (var i = 0; i < 5; i++) {
		  await sleep(1000);
		  console.log(new Date, i);
		 }
		 
		 await sleep(1000);
		 console.log(new Date, i);
		})();

		var start = async function () {
		    // 在这里使用起来就像同步代码那样直观
		    console.log('start');
		    await sleep(3000);
		    console.log('end');
		};
		start();
	</script>
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原文地址:https://www.cnblogs.com/xutongbao/p/9924908.html