在 jQuery.when 中链接多个“then”
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Chain multiple "then" in jQuery.when
提问by Lucas Sampaio
I have a function that does something like this:
我有一个函数可以做这样的事情：
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:
因此，当有人使用 时do_something，他们还可以链接更多回调，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_elseto 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从do_something_else描述的匿名函数的原始返回。我不想接收列表，而是接收位置参数，因此“当 foo”向 do_something_else 的 _foo 插入一些值，然后将相同的值插入 _foo_2。
How can I do it in JS?
我怎么能在JS中做到这一点？
回答by Kevin B
Use an anonymous function inside of .thenand pass the parameters that you want to pass. I'm replacing .thenwith .donebecause you don't need .thenin this case.
在里面使用匿名函数.then并传递您要传递的参数。我替换.then为.done因为.then在这种情况下你不需要。
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:
.then 实际上创建了一个新的延迟对象并将其发送到链。由于您没有从 返回任何内容.then，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.
如果您只是使用.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 .thenis chaining ajax requests:
最常见的用途.then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 .thenwill have access to the returned data from the previous request.
这也可以在循环中轻松完成。每个人.then都可以访问从前一个请求返回的数据。
