Friday, 22 May 2015

The Javascript Closure Problem

Swami Gulagulaananda said:
"Closure is very important in broken relationships... Also in JavaScript"

I was trying to write a fairly simple piece of code where I would create an array of functions in JavaScript. There was a loop and a function would be generated in each iteration such that the body of the function had a dependency on the loop counter. What happened finally was that every function in the loop was the same as the last function. I was bewildered. I understood that it was because of some reference issue but could not come up with a solution easily.

Here is a simple piece of code:

I was expecting a[0]() to give 0, a[1]() to give 1 and so on. But I was getting 3 each time. How do you solve this?

After breaking my head for some time (despite knowing it was something to do with Closures) I posted the question on Stackoverflow. Try solving this problem by yourself before seeing the solution.

Here's the solution: