标签：
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>$.when</title>
<script src="http://the5fireblog.b0.upaiyun.com/staticfile/jquery-1.10.2.js"></script>
<script>
function fn1(){
setTimeout(alert("fn1"),5000);
}
$.when(fn1()).done(function(){
alert("fn1执行完毕！")
}).fail(function(){
alert("出错了！")
})
</script>
</head>
<body>
</body>
</html>
但是，这样写的话，done()方法会立即执行，起不到回调函数的作用。原因在于$.when()的参数只能是deferred对象，所以必须对wait()进行改写：
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>$.when</title>
<script src="http://the5fireblog.b0.upaiyun.com/staticfile/jquery-1.10.2.js"></script>
<script>
/*function fn1(){
setTimeout(alert("fn1"),5000);
}
$.when(fn1()).done(function(){
alert("fn1执行完毕！")
}).fail(function(){
alert("出错了！")
})*/
var dtd = $.Deferred();//新建一个Deferred对象
var wait = function(dtd){
var test = function(){
alert("test执行完毕！");
// dtd.resolve();//改变deferred对象的状态
dtd.reject();
}
setTimeout(test, 5000);
return dtd;
}
$.when(wait(dtd)).done(function(){
alert("成功！")
}).fail(function(){
alert("失败！")
})
</script>
</head>
<body>
</body>
</html>
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>$.when</title>
<script src="http://the5fireblog.b0.upaiyun.com/staticfile/jquery-1.10.2.js"></script>
<script>
var wait = function(){
var dtd = $.Deferred();//新建一个Deferred对象
var test = function(){
alert("test执行完毕！");
dtd.resolve();//改变deferred对象的状态
// dtd.reject();
}
setTimeout(test, 2000);
return dtd.promise();//返回promise对象
}
// var d = wait(dtd);//新建一个d对象，以为对这个对象进行操作
$.when(wait()).done(function(){
alert("成功！")
}).fail(function(){
alert("失败！")
})
// dtd.resolve();
// d.resolve();//promise对象不能resolve,这个语句无效
</script>
</head>
<body>
</body>
</html>
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>$.when</title>
<script src="http://the5fireblog.b0.upaiyun.com/staticfile/jquery-1.10.2.js"></script>
<script>
var wait = function(){
var test = function(){
alert("test执行完毕！");
}
setTimeout(test, 2000);
}
$.Deferred(wait).done(function(){
alert("成功！")
}).fail(function(){
alert("失败！")
})
</script>
</head>
<body>
</body>
</html>
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原文地址：http://www.cnblogs.com/darr/p/4761191.html
