在jQuery.when中链多个“then”

I have a function that does something like this:

我有一个像这样的功能：

function do_something() {
    // some code

    return $.when(foo, bar, baz).then(do_something_else);
}

function do_something_else(_foo, _bar, _baz) {
    // do something else

    return /* the original inputs */;
}

So, when someone uses do_something, they can also chain more callbacks, like:

所以，当有人使用do_something时，他们也可以链接更多的回调，例如：

do_something().then(function(_foo_2, _bar_2, _baz_2) {
    console.log(_foo_2, _bar_2, _baz_2);
});

The problem is that I don't know how to bypass the original return from do_something_else to the anonymous function described. I don't want to receive a list, but positional arguments instead, so "when foo" inserts some value to do_something_else's _foo and then the same value goes to _foo_2.

问题是我不知道如何绕过do_something_else的原始返回到所描述的匿名函数。我不想收到列表，而是接收位置参数，所以“当foo”为do_something_else的_foo插入一些值，然后相同的值转到_foo_2。

How can I do it in JS?

我怎么能在JS中做到这一点？

1 个解决方案

#1

Use an anonymous function inside of .then and pass the parameters that you want to pass. I'm replacing .then with .done because you don't need .then in this case.

在.then中使用匿名函数并传递要传递的参数。我正在用.done替换。然后因为你不需要。然后在这种情况下。

function do_something() {
    // some code

    return $.when(foo, bar, baz).done(function(_foo_2, _bar_2, _baz_2){
        do_something_else.apply(this,_foo_2);
    });
}

.then actually creates a new deferred object and sends that to the chain. Since you didn't return anything from .then, the new deferred object has no arguments. See this example:

。然后实际创建一个新的延迟对象并将其发送到链。由于您没有从.then返回任何内容，因此新的延迟对象没有参数。看这个例子：

$.when($.Deferred().resolve(2), $.Deferred().resolve(4))
.then(function(a,b) { 
    console.log(a,b); // 2,4
    return $.Deferred().resolve(a,b,6);
}).then(function(a,b,c) { 
    console.log(a,b,c); // 2,4,6
});

If you instead just used .done, it would work as expected.

如果您只使用.done，它将按预期工作。

$.when($.Deferred().resolve(2), $.Deferred().resolve(4))
.done(function(a,b) { 
    console.log(a,b);
}).done(function(a,b) { 
    console.log(a,b);
});

The most common use for .then is chaining ajax requests:

.then最常见的用途是链接ajax请求：

$.ajax({...}).then(function(){
    return $.ajax({...});
}).then(function(){
    return $.ajax({...});
}).then(function(){
    return $.ajax({...});
}).then(function(){
    return $.ajax({...});
});

which can also be easily done in a loop. Each .then will have access to the returned data from the previous request.

这也可以在循环中轻松完成。每个.then都可以访问上一个请求中返回的数据。

#1