JavaScript Anonymous Function With Parameters From Call()

Question

I am trying to do the following:

function main(callback) {
   $.ajax('server-side', function() {
       this.callback.call("hello");
   }.bind({ callback: callback });
}

main(function(response) {
   alert(response);
});

Response is undefined, I would expect it to be "hello". Any ideas why?

you wrote "print response" , but print doesnt exist in javascript. — mpm
– mpm, Commented Apr 4, 2012 at 6:42

mmarinero · Accepted Answer · 2012-04-04 06:43:37Z

4

call first argument should be a reference to "this". Being "this" the context where you want to execute your function. Call function Mozila MDN

answered Apr 4, 2012 at 6:43

mmarinero

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1 Comment

nnnnnn Over a year ago

You can omit the .call part and just say this.callback("hello"). And you can omit all of the bind stuff and just use the callback parameter directly as callback("hello").

mpm · Accepted Answer · 2012-04-04 06:54:08Z

1

You wrote :

function main(callback) {
   $.ajax('server-side', function() {
       this.callback.call("hello");
   }.bind({ callback: callback });
}

main(function(response) {
   print response;
});

print doesnt exists in javascript.

then you wrote this.callback.call , which is wrong

you should write

callback.call(this,"hello") ,

just check the call function signature.

edited Apr 4, 2012 at 6:54

answered Apr 4, 2012 at 6:45

mpm

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2 Comments

Justin Over a year ago

Actually need this because of the bind() and bindding an object containing the callback. Need to use bind() because by the time the callback fires from the ajax event the passed in parameter callback will be out of scope.

nnnnnn Over a year ago

@Justin - the main() function's callback parameter will still be accessible when the ajax callback runs, even though main() will have finished by then, due to the magic of closures. Try it and see...

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