jQuery ajax成功回调的范围？

Question

if I have

function AjaxRequest(){
    var testvar = 0;
    for(i=0;i<d.length;i++){
        $.ajax({
            success: function(a){
                testvar++;
            }

        });
    }
}

Will testvar increase on success?

Answer 1

Yes; the variable is captured by the function's closure.
Closures keep variables alive so that nested functions can still use them later.

Note that the success callbacks only run some time after the rest of your code finishes (AJAX is asynchronous).

Answer 2

Yes, it will. It's similar to this:

function() {
   var self = this;
    this.a = function(){
        self.something;
    }
}