Deferred Object
function f1() {
var dfd = $.Deferred();
setTimeout(function () {
dfd.resolve();// resolved, rejected, or still in progress.
}, 500);
return dfd.promise();
}
f1().done(function () {
console.log("Hello World !")
}).fail(function () {
console.log("Error")
});
var wait = function (dtd) {
setTimeout(function () {
dtd.resolve();//表示处理结束, 调用后立即执行.done方法
//dtd.reject();//标识处理失败,调用后立即执行fail方法
}, 500);
return dtd.promise();
};
//使用$.when()为普通操作添加回调函数 为多个操作指定回调函数
//$.when(deferred, deferred,...)：多有的延迟对象都调用了resolve()时才执行done；只要有一个延迟对象调用了reject()就会执行fail()。
//如果参数不是延迟对象就会跳过该参数并代表成功，如果参数都不是延迟对象，也会成功，会执行done。
//成功或失败的回调函数的参数对应when中的参数，如果参数是延迟对象回调函数得到undefined，不是延迟对象得到参数值。
//done中的方法可以接受参数由when调用的方法返回
var dtd = $.Deferred();
$.when(wait(dtd), wait(dtd))
.done(function (p1, p2) {
console.log("when 多个方法执行成功 ")
})
.fail(function () {
console.log("Error")
});
//还可以直接在wait对象上部署deferred接口。
$.Deferred(wait)
.done(function () {
console.log("Success ")
})
.fail(function () {
console.log("Error")
});
// 为了省事，可以把done()和fail()合在一起写，这就是then()方法。
$.Deferred(wait)
.then(function () {
console.log("Success ")
}, function () {
console.log("Error")
}).always(function () {
console.log("总是执行的方法");
});
/* 如果then()有两个参数，那么
第一个参数是done()方法的回调函数，
第二个参数是fail()方法的回调方法。
如果then()
只有一个参数，那么等同于done()。*/
deferred.always()
Add handlers to be called when the Deferred object is either resolved or rejected.
deferred.done()
Add handlers to be called when the Deferred object is resolved.
deferred.fail()
Add handlers to be called when the Deferred object is rejected.
deferred.isRejected()
Determine whether a Deferred object has been rejected.
deferred.isResolved()
Determine whether a Deferred object has been resolved.
deferred.notify()
Call the progressCallbacks on a Deferred object with the given args.
deferred.notifyWith()
Call the progressCallbacks on a Deferred object with the given context and args.
deferred.pipe()
Utility method to filter and/or chain Deferreds.
deferred.progress()
Add handlers to be called when the Deferred object generates progress notifications.
deferred.promise()
Return a Deferred’s Promise object.
deferred.reject()
Reject a Deferred object and call any failCallbacks with the given args.
deferred.rejectWith()
Reject a Deferred object and call any failCallbacks with the given context and args.
deferred.resolve()
Resolve a Deferred object and call any doneCallbacks with the given args.
deferred.resolveWith()
Resolve a Deferred object and call any doneCallbacks with the given context and args.
deferred.state()
Determine the current state of a Deferred object.
deferred.then()
Add handlers to be called when the Deferred object is resolved, rejected, or still in progress.
jQuery.Deferred()
A factory function that returns a chainable utility object with methods to register multiple callbacks into callback queues, invoke callback queues, and relay the success or failure state of any synchronous or asynchronous function.
jQuery.when()
Provides a way to execute callback functions based on one or more objects, usually Deferred objects that represent asynchronous events.
.promise()
Return a Promise object to observe when all actions of a certain type bound to the collection, queued or not, have finished.