declaration for variable in while condition in javascript

Question

In essence, I am trying to declare a variable in the condition-part of a while loop in javascript:

while (var b=a.pop()) {
  do_sth(b)
}

Yet, my browser (firefox) doesn't accept that. Instead I have to go like so:

var b
while (b=a.pop()) {
  do_sth(b)
}

which works. Is this behaviour expected?

question from:https://stackoverflow.com/questions/1711173/declaration-for-variable-in-while-condition-in-javascript

Answer 1

Yes, it is.

If you want to, you can use a for loop, like this:

for (var b; b = a.pop(); ) {      //Note the final semicolon
    do_sth(b);
}