ash ash - 13 days ago 4
Ajax Question

jQuery pass more parameters into callback

Is there a way to pass more data into a callback function in jQuery?

I have two functions and I want the callback to the

, for example, to pass in both the resulting data of the AJAX call, as well as a few custom arguments

function clicked() {
var myDiv = $("#my-div");
// ERROR: Says data not defined
$.post("someurl.php",someData,doSomething(data, myDiv),"json");
// ERROR: Would pass in myDiv as curData (wrong)
$.post("someurl.php",someData,doSomething(data, myDiv),"json");

function doSomething(curData, curDiv) {


I want to be able to pass in my own parameters to a callback, as well as the result returned from the AJAX call.



The solution is the binding of variables through closure.

I haven't used the .post function in jQuery, but a quick scan of the documentation suggests the call back should be a function pointer accepting the following:

function callBack(data, textStatus, jqXHR) {};

Therefore I think the solution is as follows:

var doSomething = function(extraStuff) {
    return function(data, textStatus, jqXHR) {
        // do something with extraStuff

var clicked = function() {
    var extraStuff = {
        myParam1: 'foo',
        myParam2: 'bar'
    }; // an object / whatever extra params you wish to pass.

    $.post("someurl.php", someData, doSomething(extraStuff), "json");

What is happening?

In the last line, doSomething(extraStuff) is invoked and the result of that invocation is a function pointer.

Because extraStuff is passed as an argument to doSomething it is within scope of the doSomething function.

When extraStuff is referenced in the returned anonymous inner function of doSomething it is bound by closure to the outer function's extraStuff argument. This is true even after doSomething has returned.

I haven't tested the above, but I've written very similar code in the last 24 hours and it works as I've described.

You can of course pass multiple variables instead of a single 'extraStuff' object depending on your personal preference/coding standards.