Does using var in a tight JavaScript loop increase memory-related overhead?

Question

For example, would this:

while (true) {
    var random = Math.random();
}

... be less efficient than the following, in most implementations?

var random;
while (true) {
    random = Math.random();
}

Thanks for your input.

Edit: In case it wasn't obvious, I'm mostly worried about lots of repeated (de)allocations occurring in this example.

Answer 1

JavaScript does not have block scoping.

In the first example, the var text declaration is hoisted out of the while block. In both cases, the variable is declared only once. In both cases, the variable is assigned a value once per iteration of the while loop.

var

• function-scoped
• hoist to the top of its function
• redeclarations of the same name in the same scope are no-ops

Answer 2

No, variables are initiated upon entry into the scope, so random exists before the var statement is even reached.

Answer 3

JavaScript doesn't have block scope, and random's declaration would be hoisted to the top of its scope anyway (variable object).