Repeating items in an array multiple times in a loop?

Question

I have an array with 6 strings representing HTML image tags. I have some code which determines an amount of space to fill with these images.

I am using a loop, which works fine to pull from these 6 images and use 1 or all 6. My issue comes when I need MORE than 6, which would mean go through the array again and again. I am unsure how to best construct this loop. Currently I have

for (var i = 0; i < numAds ; i++) {
            $('#primary').append(adList[i]);
        };

I tried adding if (i > adList.length) { i=0 } before the jquery statement but then I got stuck in a loop and crashed the browser.

What am I missing here?

Gabriele Petrioli · Accepted Answer · 2012-12-28 17:01:15Z

6

Use

$('#primary').append(adList[i % adList.length]);

The % is the modulus operator

Make sure, though, that adList is not empty or that would cause the i % adList.length to return NaN and ~~crash~~ make the adList[i % adList.length] return undefined what whatever sideffects this might bring.

edited Dec 28, 2012 at 17:01

answered Dec 28, 2012 at 16:41

Gabriele Petrioli

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8 Comments

Ricardo Lohmann Over a year ago

You can also remove append from loop.

Nope Over a year ago

If i = 0 would i % adList.length not result in NaN ?

Nope Over a year ago

@GabyakaG.Petrioli: Ah yes, I got it the wrong way around i % 0 would be NaN. Sorry about that, my bad.

Shmiddty Over a year ago

@FrançoisWahl i % 0 would be dividing by zero... obviously this results in NaN.

Shmiddty Over a year ago

@Steve Modulus is the remainder of a division operation. By definition, this means that the return value is limited to values between 0 and the denominator (never equaling the denominator).

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