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JavaScript

Posted by jason chan
jason chan
31,009 Points

So how does this while loop work for 2^10

var result = 1;
var counter = 0;
while (counter < 10) {
  result = result * 2;
  counter = counter + 1;
}
console.log(result);
// → 1024

someone explain to me what's happening here?

kind of lost when result = result * 2;

why is var result = 1?

2 Answers

Nick Novak
Nick Novak
2,517 Points

What we are essentially doing is taking 2^10 by running it as a loop.

First lets look at powers:

2^10 = 2*2*2*2*2*2*2*2*2*2 think of each * as a loop.

Each iteration of of result = result * 2 will times the next number by 2.

so lets break it down by each iteration:

iteration 1: result(1) = result(1) * 2; result = 2; counter =1
iteration 2: result(2) = result(2) * 2; result = 4; counter =2
iteration 3: result(4) = result(4) * 2; result = 8; counter =3
iteration 3: result(8) = result(8) * 2; result = 16; counter =3...
and so forth until our counter reaches 10 and the result equals 1024.

With result = 1, it has to be to get the correct results.

lets take the first example but make result = 0:

iteration 1: result(0) = result(0) * 2. result becomes = 0; counter =1
iteration 2: result(0) = result(0) * 2. result becomes = 0; counter =2
iteration 3: result(0) = result(0) * 2. result becomes = 0; counter =3...
and so forth until our counter reaches 10 and the result equals 0. result has to have a starting point at one for powers to work..

jason chan
jason chan
31,009 Points

thankyou very much!

Jeff Lemay
Jeff Lemay
14,268 Points
Jeff Lemay
Jeff Lemay
14,268 Points

Fantastic answer in comments

Nick Novak
Nick Novak
2,517 Points

Whoops. I meant to place that in the answers section. I have it in there now.