Is it good practice to set variables to null when they are no longer needed?

Question

I have seen javascript values set to null at the end of a function. Is this done to reduce memory usage or just to prevent accidental usage elsewhere?

Is there a good case for doing this. If so when?

var myValue; . . . myValue = null; 

Answer 1

It wouldn't make any difference setting a local variable to null at the end of the function because it would be removed from the stack when it returns anyway.

However, inside of a closure, the variable will not be deallocated.

var fn = function() {     var local = 0;     return function() {       console.log(++local);    }  }  var returned = fn();  returned(); // 1 returned(); // 2 

jsFiddle.

When the inner function is returned, the outer variable's scope will live on, accessible to the returned inner function.