How is data passed to anonymous functions in JavaScript?

Question

When I pass \'this\' to an anonymous function like so:

MyClass.prototype.trigger = function(){
    window.setTimeout(function(){this.onTimeout();},1000);
}
         


        

Answer 1

You are confused about the closures.

For the first problem, yes, you are right, that is the way it can be done. The only difference that there is a convention to name the variable that that holds this.

MyClass.prototype.trigger = function(){
    var that = this;
    window.setTimeout(function(){that.onTimeout();},1000);
}

There is already a nice thread about this on StackOverflow. Check answers for question How does a javascript closure work?.

Your second problem is an exact duplicate of Javascript closure inside loops - simple practical example.