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zhengwei1949 / myblog

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理解callback #147

Open zhengwei1949 opened 5 years ago

zhengwei1949 commented 5 years ago 
<!DOCTYPE html>
<html lang="en">
<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>Document</title>
</head>
<body>
    <script>
        console.log('我要回家了');
        setTimeout(function(){
            console.log('我到家了');
            console.log('我吃的关东煮');
            console.log('我睡觉了');
        },2000);

        console.log('我要回家了');
        setTimeout(function(){
            console.log('我洗澡了');
            console.log('我到家了');
            console.log('我睡觉了');
        },3000);

        function goHome(){
            console.log('我要回家了');
            setTimeout(function () {
                console.log('我到家了');
                console.log('我吃的关东煮');
                console.log('我睡觉了');
            }, 2000);
        }

        function goHome1(time){
            console.log('我要回家了');
            setTimeout(function () {
                console.log('我到家了');
                console.log('我吃的关东煮');
                console.log('我睡觉了');
            }, time);
        }

        function goHome2(time){
            console.log('我要回家了');
            setTimeout(function () {
                var fn = function(){
                    console.log('我到家了');
                    console.log('我吃的关东煮');
                    console.log('我睡觉了');
                }
                fn();
            }, time);
        }

        var fn = function(){
            console.log('我到家了');
            console.log('我吃的关东煮');
            console.log('我睡觉了');
        }
        function goHome3(time){
            console.log('我要回家了');
            setTimeout(function () {
                fn();
            }, time);
        }

        var fn = function(){
            console.log('我到家了');
            console.log('我吃的关东煮');
            console.log('我睡觉了');
        }
        function goHome3(time,fn){
            console.log('我要回家了');
            setTimeout(function () {
                fn();
            }, time);
        }

        var fn = function(){
            console.log('我到家了');
            console.log('我吃的关东煮');
            console.log('我睡觉了');
        }
        function goHome3(time,callback){
            console.log('我要回家了');
            setTimeout(function () {
                callback();
            }, time);
        }

        var fn = function(){
            console.log('我到家了');
            console.log('我吃的关东煮');
            console.log('我睡觉了');
        }
        function goHome3(time,callback){
            console.log('我要回家了');
            setTimeout(function () {
                if(callback){
                    callback();
                }
            }, time);
        }

        var fn = function(){
            console.log('我到家了');
            console.log('我吃的关东煮');
            console.log('我睡觉了');
        }
        function goHome3(time,callback){
            console.log('我要回家了');
            setTimeout(function () {
                if(typeof callback == 'function'){
                    callback && callback();
                }
            }, time);
        }

    </script>
</body>
</html>