我需要传递一个额外的参数给 .done 承诺一个jquery Ajax调用回调函数：

  $。员额（MyUrl，JSON.stringify（数据））
        .done（onMyUrlLoaded）;
 

标准的回调，会是这样的：

 函数onMyUrlLoaded（数据，textStatus，jqXHR）{/ *函数code * /};
 

但我需要一个额外的参数传递给我的回调，像这样的：

 函数onMyUrlLoaded（数据，textStatus，jqXHR，extraParam）{/ * code * /};
 

我该怎么办呢？

我发现它真的很容易，包括一个新的水平间接，就像这样：

  VAR extraParam ='某某';

$。员额（MyUrl，JSON.stringify（数据））
        .done（功能（A，B，C）{onMyUrlLoaded（A，B，C，extraParam）;}）;
 

在这种方式中，回调将收到extraParam，除了三个标准参数

当然，这也可以做，如果承诺被存储在一个变量，例如，一个通过函数返回，就像这样：

 函数的getURL（）{
  //一些code ...
  VAR承诺= $。员额（MyUrl，JSON.stringify（数据））;
  返回的承诺;
}
 

这可以被调用和使用这样的：

  VAR承诺=的getURL（）;
VAR extraParam ='某某';
promise.done（功能（A，B，C）{onMyUrlLoaded（A，B，C，extraParam）;}）;
 

有这样做，其由在使用较短的语法绑定。

当你调用绑定的功能，你会得到一个新的功能。通过绑定的第一个参数将成为这德返回功能的体内。其他参数将是 prepended 以原来的参数。

下面code展示了如何使用绑定。对于TL; DR期待的code中的最后两个块

I need to pass an extra parameter to the .done promise callback of a jquery ajax call:

$.post("MyUrl", JSON.stringify(data))
        .done(onMyUrlLoaded);

The standard callback, would be like this:

function onMyUrlLoaded(data, textStatus, jqXHR) { /* function code */ };

But I need to pass an extra parameter to my callback, like this:

function onMyUrlLoaded(data, textStatus, jqXHR, extraParam) { /* code */ };

How can I do it?

I've discovered that it's really easy including a new indirection level, just like this:

var extraParam = 'xyz';

$.post("MyUrl", JSON.stringify(data))
        .done(function(a,b,c) { onMyUrlLoaded(a, b, c, extraParam); });

In this way, the callback will receive the extraParam, besides the three standard parameters.

Of course, this can also be done if the promise is stored in a variable, for example one returned by a function, like this:

function getUrl() {
  // some code ...
  var promise = $.post("MyUrl", JSON.stringify(data));
  return promise;
}

This can be invoked and used like this:

var promise = getUrl();
var extraParam = 'xyz';
promise.done(function(a,b,c) { onMyUrlLoaded(a, b, c, extraParam); });

There is a shorter syntax for doing this, which consist in using bind.

When you call bind in a function, you get a new function. The first parameter passed to bind will become this inside the body of teh return function. The additional parameters will be prepended to the original arguments.

The following code shows how to use bind. For TL;DR look the two last blocks of code

// To show the results in the page
var $log = $('#log');
var log = function(text) {
    $log.append(text+'<br/>');
};

// This returns a promise, and resolves it after the specified
// timeout. This behaves like a jQuery ajax call (but for the
// provided timeout)
var trigger = function(timeout) {
    log('<b>trigger</b> invoked');
    var deferred = $.Deferred();
    setTimeout(function() {
        log('<b>trigger</b> resolving promise');
        deferred.resolve('A','B');
    }, timeout);
    return deferred;
};

// This is the function we want to invoke
// The promise returns a and b - the extra params
// must be supplied in some way
var extraParams = function(extra1, extra2, a, b) {
    log('<b>extraParams</b> extra1:' + extra1);
    log('<b>extraParams</b> extra2:' + extra2);
    log('<b>extraParams</b> a:' + a);
    log('<b>extraParams</b> b:' + b);
};


// Doing it using indirection
trigger(500).then(function(a,b) {
  extraParams('extra1','extra2',a,b);
});

// Doing it using bind()
trigger(1200).then(
  extraParams.bind(this,'extra1','extra2')
);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="log">
</div>