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promise 执行顺序

1、代码

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8" />
        <title>promise 执行</title>
    </head>
    <body>
        <script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.22.2/moment.js"></script>
        <script type="text/javascript">
            function delay(time) {
                return new Promise(function(resolve, reject) {
                    setTimeout(resolve, time)
                })
            }
            delay(1000)
                .then(function step2() {
                    console.log('step 2: after 1000ms');
                    return delay(2000)
                })
                .then(function step3() {
                    console.log('step 3: after another 2000ms');
                })
                .then(function step4() {
                    console.log('step 4: next job');
                    return delay(5000)
                })
                .then(function step5() {
                    console.log('step 5: after another 5000ms');
                })
        </script>
    </body>
</html>

控制台输出：

2、说明

promise将执行结果（不管是resolve还是reject），传到then和catch中。

posted @ 2018-11-07 11:17  孟繁贵  阅读(1834)  评论(0)  编辑  收藏  举报
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