jQuery pass more parameters into callback
JavascriptJqueryFunctionCallbackArgumentsJavascript Problem Overview
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 $.post
, 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.
Javascript Solutions
Solution 1 - Javascript
The solution is the binding of variables through closure.
As a more basic example, here is an example function that receives and calls a callback function, as well as an example callback function:
function callbackReceiver(callback) {
callback("Hello World");
}
function callback(value1, value2) {
console.log(value1, value2);
}
This calls the callback and supplies a single argument. Now you want to supply an additional argument, so you wrap the callback in closure.
callbackReceiver(callback); // "Hello World", undefined
callbackReceiver(function(value) {
callback(value, "Foo Bar"); // "Hello World", "Foo Bar"
});
Or, more simply using ES6 Arrow Functions:
callbackReceiver(value => callback(value, "Foo Bar")); // "Hello World", "Foo Bar"
As for your specific example, 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 with the following signature:
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.
Solution 2 - Javascript
When using doSomething(data, myDiv)
, you actually call the function and do not make a reference to it.
You can either pass the doStomething
function directly but you must ensure it has the correct signature.
If you want to keep doSomething the way it is, you can wrap its call in an anonymous function.
function clicked() {
var myDiv = $("#my-div");
$.post("someurl.php",someData, function(data){
doSomething(data, myDiv)
},"json");
}
function doSomething(curData, curDiv) {
...
}
Inside the anonymous function code, you can use the variables defined in the enclosing scope. This is the way Javascript scoping works.
Solution 3 - Javascript
It's actually easier than everyone's making it sound... especially if you use the $.ajax({})
base syntax vs. one of the helper functions.
Just pass in the key: value
pair like you would on any object, when you setup your ajax request... (because $(this)
hasn't changed context yet, it's still the trigger for the bind call above)
<script type="text/javascript">
$(".qty input").bind("keypress change", function() {
$.ajax({
url: "/order_items/change/"+$(this).attr("data-order-item-id")+"/qty:"+$(this).val()+"/returnas.json",
type: "POST",
dataType: "json",
qty_input: $(this),
anything_else_i_want_to_pass_in: "foo",
success: function(json_data, textStatus, jqXHR) {
/* here is the input, which triggered this AJAX request */
console.log(this.qty_input);
/* here is any other parameter you set when initializing the ajax method */
console.log(this.anything_else_i_want_to_pass_in);
}
});
});
</script>
One of the reasons this is better than setting the var, is that the var is global and as such, overwritable... if you have 2 things which can trigger ajax calls, you could in theory trigger them faster than ajax call responds, and you'd have the value for the second call passed into the first. Using this method, above, that wouldn't happen (and it's pretty simple to use too).
Solution 4 - Javascript
In today's world there is a another answer that is cleaner, and taken from another Stack Overflow answer:
function clicked()
{
var myDiv = $( "#my-div" );
$.post( "someurl.php", {"someData": someData}, $.proxy(doSomething, myDiv), "json" );
}
function doSomething( data )
{
// this will be equal to myDiv now. Thanks to jQuery.proxy().
var $myDiv = this;
// doing stuff.
...
}
Here's the original question and answer: https://stackoverflow.com/questions/2602981/jquery-how-to-pass-additional-parameters-to-success-callback-for-ajax-call
Solution 5 - Javascript
You can also try something like the following:
function clicked() {
var myDiv = $("#my-div");
$.post("someurl.php",someData,function(data){
doSomething(data, myDiv);
},"json");
}
function doSomething(curData, curDiv) {
}
Solution 6 - Javascript
You can use a closure of JavaScript:
function wrapper( var1, var2,....) // put here your variables
{
return function( data, status)
{
//Handle here results of call
}
};
and when you can do:
$.post("someurl.php",data,wrapper(var1, var2, etc...),"html");
Solution 7 - Javascript
I've made a mistake in the last my post. This is working example for how to pass additional argument in callback function:
function custom_func(p1,p2) {
$.post(AJAX_FILE_PATH,{op:'dosomething',p1:p1},
function(data){
return function(){
alert(data);
alert(p2);
}(data,p2)
}
);
return false;
}
Solution 8 - Javascript
Let's go simple ! :)
$.ajax({
url: myUrl,
context: $this, // $this == Current $element
success: function(data) {
$.proxy(publicMethods.update, this)(data); // this == Current $element
}
});
Solution 9 - Javascript
A more general solution for sending asynchronous requests using the .ajax()
jQuery API and closures to pass additional parameters to the callback function:
function sendRequest(method, url, content, callback) {
// additional data for the callback
var request = {
method: method,
url: url
};
$.ajax({
type: method,
url: url,
data: content
}).done(function(data, status, xhr) {
if (callback) callback(xhr.status, data, request);
}).fail(function(xhr, status) {
if (callback) callback(xhr.status, xhr.response, request);
});
};
Solution 10 - Javascript
For me, and other newbies who has just contacted with Javascript,
I think that the Closeure Solution
is a little kind of too confusing.
While I found that, you can easilly pass as many parameters as you want to every ajax callback using jquery.
Here are two easier solutions.
First one, which @zeroasterisk has mentioned above, example:
var $items = $('.some_class');
$.each($items, function(key, item){
var url = 'http://request_with_params' + $(item).html();
$.ajax({
selfDom : $(item),
selfData : 'here is my self defined data',
url : url,
dataType : 'json',
success : function(data, code, jqXHR){
// in $.ajax callbacks,
// [this] keyword references to the options you gived to $.ajax
// if you had not specified the context of $.ajax callbacks.
// see http://api.jquery.com/jquery.ajax/#jQuery-ajax-settings context
var $item = this.selfDom;
var selfdata = this.selfData;
$item.html( selfdata );
...
}
});
});
Second one, pass self-defined-datas by adding them into the XHR object
which exists in the whole ajax-request-response life span.
var $items = $('.some_class');
$.each($items, function(key, item){
var url = 'http://request_with_params' + $(item).html();
$.ajax({
url : url,
dataType : 'json',
beforeSend : function(XHR) {
// 为了便于回调,把当前的 jquery对象集存入本次 XHR
XHR.selfDom = $(item);
XHR.selfData = 'here is my self defined data';
},
success : function(data, code, jqXHR){
// jqXHR is a superset of the browser's native XHR object
var $item = jqXHR.selfDom;
var selfdata = jqXHR.selfData;
$item.html( selfdata );
...
}
});
});
As you can see these two solutions has a drawback that : you need write a little more code every time than just write:
$.get/post (url, data, successHandler);
Read more about $.ajax : http://api.jquery.com/jquery.ajax/
Solution 11 - Javascript
$(document).on('click','[action=register]',function(){
registerSocket(registerJSON(),registerDone,second($(this)));
});
function registerSocket(dataFn,doneFn,second){
$.ajax({
type:'POST',
url: "http://localhost:8080/store/public/register",
contentType: "application/json; charset=utf-8",
dataType: "json",
data:dataFn
}).done ([doneFn,second])
.fail(function(err){
console.log("AJAX failed: " + JSON.stringify(err, null, 2));
});
}
function registerDone(data){
console.log(JSON.stringify(data));
}
function second(element){
console.log(element);
}
Secondary way :
function socketWithParam(url,dataFn,doneFn,param){
$.ajax({
type:'POST',
url:url,
contentType: "application/json; charset=utf-8",
headers: { 'Authorization': 'Bearer '+localStorage.getItem('jwt')},
data:dataFn
}).done(function(data){
doneFn(data,param);
})
.fail(function(err,status,xhr){
console.log("AJAX failed: " + JSON.stringify(err, null, 2));
});
}
$(document).on('click','[order-btn]',function(){
socketWithParam(url,fakeDataFn(),orderDetailDone,secondParam);
});
function orderDetailDone(data,param){
-- to do something --
}
Solution 12 - Javascript
If someone still comes here, this is my take:
$('.selector').click(myCallbackFunction.bind({var1: 'hello', var2: 'world'}));
function myCallbackFunction(event) {
var passedArg1 = this.var1,
passedArg2 = this.var2
}
What happens here, after binding to the callback function, it will be available within the function as this
.
This idea comes from how React uses the bind
functionality.
Solution 13 - Javascript
actually, your code is not working because when you write:
$.post("someurl.php",someData,doSomething(data, myDiv),"json");
you place a function call as the third parameter rather than a function reference.
Solution 14 - Javascript
As an addendum to b01's answer, the second argument of $.proxy
is often used to preserve the this
reference. Additional arguments passed to $.proxy
are partially applied to the function, pre-filling it with data. Note that any arguments $.post
passes to the callback will be applied at the end, so doSomething
should have those at the end of its argument list:
function clicked() {
var myDiv = $("#my-div");
var callback = $.proxy(doSomething, this, myDiv);
$.post("someurl.php",someData,callback,"json");
}
function doSomething(curDiv, curData) {
//"this" still refers to the same "this" as clicked()
var serverResponse = curData;
}
This approach also allows multiple arguments to be bound to the callback:
function clicked() {
var myDiv = $("#my-div");
var mySpan = $("#my-span");
var isActive = true;
var callback = $.proxy(doSomething, this, myDiv, mySpan, isActive);
$.post("someurl.php",someData,callback,"json");
}
function doSomething(curDiv, curSpan, curIsActive, curData) {
//"this" still refers to the same "this" as clicked()
var serverResponse = curData;
}