return String vs Integer vs undefined vs null

Question

Why does javascript prefers to return a String over any other choices ?

Consider the following snippet.

var arr = [\'Hello1\', \'Hello2\', \         


        

Answer 1

The statement

return this[x] || null || 'aïe' || 12 || undefined ;

will evaluate the subexpressions left to right, and will return the first subexpression that does not evaluate to false. The non-existent element evaluates to false as it's undefined, and null is false by definition. That leaves the string as the first non-false subexpression, so that's what you get.