A for loop without any {}

Question

So I was reading about shuffling an array. And then I came across this script:

shuffle = function(o){ //v1.0
    for(var j, x, i = o.length; i; j = parseInt(         


        

Answer 1

All the work is actually being done within the parens of the for statement. There is not explicit body for the loop so the ; at the end just says that the body is an empty statement.

The , (comma) operator evaluates expressions from left to right, and returns the value of the right-most.

The loop is basically equivalent to:

for(var j, x, i = o.length; i > 0;)
{
    j = parseInt(Math.random() * i--);
    x = o[i];
    o[i] = o[j];
    o[j] = x
}