CODEWITHSUNDEEP
jquerycallback
Mohammed H
Mohammed H

Reputation: 7048

How to pass variable to a callback function

function firstCallme(iWantToBePassed) {

   post(callbackFun);
}

// This function shouldn't be anonymous.
function callbackFun(dataFromPostFun) {

 alert(iWantToBePassed);
}

How to pass the variable iWantToBePassed from firstCallme() to callbackFun()? There are several similiar question in SO. But I couldn't identify the solution from it.

I know only one solution as given below:

function firstCallme(iWantToBePassed) {

   post(function(data){callbackFun(data,iWantToBePassed) });
}

// This function shouldn't be anonymous.
function callbackFun(dataFromPostFun, iWantToBePassed) {

 alert(iWantToBePassed);
}

Is there any better solution?

UPDATE:

here:

function post(callbackFun) {
  jQuery.post('url', 'data', callbackFun, 'json');    
}

Upvotes: 2

Views: 519

Answers (4)

Hans Vn
Hans Vn

Reputation: 844

Just call the callbackFun function with the parameter to should be passed.

The parameter after the function is what is posted, you don't have to tell the JavaScript browser to post something, it already knows it has to post (pass) a variable to a function when it is declared between the parentheses.

function firstCallme(iWantToBePassed) {
    callbackFun(iWantToBePassed);
}

function callbackFun(dataFromPostFun) {
   alert(dataFromPostFun);
}

*edit:

The jQuery.post function is an asynchronous javascript call (to get data without a page load).

So when used jQuery.post you can pass parameters to a php script for example and get an answer from it. A short-hand function for this is $.ajax() for example.

With jQuery.post you send 'data' to an 'url' and the 'callbackFunction' is the function that handles the answer. the 'json' in your question is the data type.

In your case this would become something like this:

function firstCallme(postData){
    jQuery.post("url.php", postData, callbackFun(data), "json");
}

callbackFun(successData){
    console.log(successData);
}

jquery.post documentation

Upvotes: 1

orandov
orandov

Reputation: 3276

Since your callback function is invoked after a post then the only way to pass parameters to the callback function is to use some form of Closure like you showed in the solution you mentioned in your question.

You can also post your parameter iWantToBePassed and retrieve it from the data in the post in your callback function. But I wouldn't recommend this route unless you need that parameter on the server.

Upvotes: 2

Jai
Jai

Reputation: 74738

Try it this way: http://jsfiddle.net/6WxfF/

function firstCallme(iWantToBePassed) {
    callbackFun(iWantToBePassed);
}

function callbackFun(dataFromPostFun) {
    post(dataFromPostFun);
}

function post(callbackFun) {
    jQuery.post('url', 'data', callbackFun, 'json');    
}

$(function() {
    var hel = "Hello";
    firstCallme(hel);
});

Upvotes: 0

techfoobar
techfoobar

Reputation: 66663

Rewrite post as:

function post(callbackFun, param) {
  jQuery.post('url', 'data', function() { callbackFun(param); }, 'json');    
}

And call it like:

function firstCallme(iWantToBePassed) {
  post(callbackFun, iWantToBePassed);
}

Upvotes: 0

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