Question

I have a problem using Class with setter using ajax. Here is the condition.

var MyClass = Class.create();
MyClass.prototype = {
    myAttr:0,
    setMyAttr: function(){
        jQuery.ajax({
            url:'data.php',
            success:function(data) {
                //set myAttr here
            }
        });
    }
}

I want to set myAttr inside the success function, how to do this? Thanks. 😀

Answer 1

You haven’t said what Class.create is (there is none in JavaScript itself), but I don’t think it matters much for the question.

I assume you want to set myAttr on the instance, not the prototype (but see below if I’m wrong). The simplest way is to take advantage of the fact that your success callback is already a closure over the context of the call to setMyAttr, so you set a variable to be this (since this will be different in the success callback) and use that:

var MyClass = Class.create();
MyClass.prototype = {
    myAttr:0,
    setMyAttr: function(){
        var self = this;            // <== Set the variable
        jQuery.ajax({
            url:'data.php',
            success:function(data) {
                self.myAttr = data; // <== Use it
            }
        });
    }
};

More on closures: Closures are not complicated

But if I’m wrong and you do actually want to update the prototype instead:

var MyClass = Class.create();
MyClass.prototype = {
    myAttr:0,
    setMyAttr: function(){
        jQuery.ajax({
            url:'data.php',
            success:function(data) {
                MyClass.prototype.myAttr = data;
            }
        });
    }
};

(Note the ; at the end of the assignment to the prototype. I strongly advocate not relying on the horror that is automatic semicolon insertion.)