Understand how CONTINUE works in Javascript?

Question

I'm reading an article on the MDN website about loops and iteration. I'm trying to understand why we are getting the 1, 3, 7, 12 as a result from the following?:

var i = 0;
var n = 0;
while (i < 5) {
 i++;
  if (i == 3) {
  continue;
  }
 n += i;
}

Wouldn't the continue statement cause it to skip 3?

You are skipping the 3rd iteration but the 3 is from `1 + 2` — Cave Johnson, May 23 '16 at 22:07

score 2 · Answer 1 · answered May 23 '16 at 22:07

What continue does is immediately jump to the top of your loop. Essentially, it ignores everything following it and moves on to the next iteration.

To give a simpler example, here's how to print only the even numbers in a range:

for (var i = 0; i < 10; i++) {
  // If i isn't even, skip to the next iteration
  if (i % 2 !== 0) {
    continue;
  }
  console.log(i);
}

Because of this, you are not adding 3 to your running sum. Instead, you essentially get:

var i = 0;
var n = 0;
i++; // 1
n += i; // 1

i++; // 2
n += i; // 3

i++; // 3
// skip 3

i++; // 4
n += i; // 7

i++; // 5
n += i; // 12

great explanation. Thanks for that! – theAussieGuy May 24 '16 at 01:44 — theAussieGuy, May 24 '16 at 01:44

score 0 · Answer 2 · answered May 23 '16 at 22:10

0

Yes. When i equals 3, the loop is skipped. The Focus is rather on n, which has the values 1, 3, 7, 12

answered May 23 '16 at 22:10

jaap-de-boer

137
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1
8

score 0 · Answer 3 · answered May 23 '16 at 22:21

I've overlooked the assignment operator in this example (+=).

As we loop it progresses as follows:

After the first loop, x=1 and y=1, we progress and add another 1 to x which now = 2. Due to the assignment operator (n += x) we add two(x) to one(y).

At this stage we loop again and the operation realises that x has become three, so it 'skips' that assignment operator and continues.

Understand how CONTINUE works in Javascript?

3 Answers3