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?

• javascript
• closures
• anonymous-function

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

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.