Javascript purpose of return false in this code?

As I said in the comment above, a function by default returns 'undefined', which for all intents and purposes is the same as returning false. So the return false here is essentially useless.

MORE:

Why is returning 'false' the same as returning 'undefined'? This has to do with the concept of 'truthiness' in JavaScript: certain values, when evaluated as 'yes' or 'no', will evaluate to true. For example:

0 = false

false = false (duh)

"false" = true (it's a string, so the browser thinks it exists, and therefore is true)

"any other string" = true

1 to infinity, or -1 to negative infinity = true

undefined = false

null = true (usually!)

So if a program were to use this return value to test something (i.e., if (!showpic(myObj)) alert('returned false!')), returning false would do the exact same thing as returning nothing (i.e., undefined).

it get back to your code and from where you call JS function