Question

I am writing a web crawler for reddit which only allows 1 request every 2 seconds and would like to use recursion to make the requests. After the series of get requests for 1 persons comments are complete, I would like to emit to show completion and call the comments again on the next username in a message queue. The problem is whenever I am more than one level deep I get a “TypeError: Object # has no method ’emit'”.

I am also open for better ways to do this, I have just started learning node and am sure there are much better ways to accomplish this.

I have posted my code in the gist below…any help would be awesome!

https://gist.github.com/1729182

Answer 1

The issue is with this which is a keyword (not free variable) that evaluates to the “receiver” for the function call.

For instance, given:

x = {fn: function () {return this} }
x.fn()

Then inside fn, this evaluates to what x evaluated to (and thus x.fn() === x). In the code grabComments is being invoked with no receiver, in which case this reverts to the global object. You may be interested in Function.call/apply, or just simplify the code to handle recursion with a nested function so that self can remain bound-to in scope.

(In JavaScript, methods are not bound to objects: they are merely functions shoved into properties, so the receiver is paramount in determining this for the executiong function.)

See also:

• jQuery/JavaScript "this" pointer confusion
• In Javascript, why is the "this" operator inconsistent?
• Javascript "this" variable confusion
• How do JavaScript closures work?

Happy coding.