Closure compiler warning on for loop

Question

I'm using a somewhat unconventional for loop that works well for what I'm doing as paraphrased below (not bothering to show variable declarations):

if (arr && arr.length > 0) {
    for (i = arr.length; i--; i) {
        element = arr.pop();
        //rest of code
    }
}

Closure compiler is giving me a warning of: "WARNING - Suspicious code. This code lacks side effects, is there a bug?" Pointing specifically to the last "i" in the for loop parens.

If I remove the i, jslint throws a warning, if I leave it, closure throws a warning. There are three of these loops in total, is there a "closure friendly" way to do this?

score 3 · Accepted Answer · answered May 25 '12 at 21:16

3

How 'bout the normal way?

if (arr && arr.length > 0) {
    for (i = arr.length; i > 0; --i) {
        element = arr.pop();
        //rest of code
    }
}

Putting the decrement in the test is just not the normal way to write a for loop.

Or even more normal:

if (arr && arr.length > 0) {
    for (i = arr.length - 1; i >= 0; --i) {
        element = arr.pop();
        //rest of code
    }
}

...but as you're not using i, it doesn't matter much.

Or you could use a while:

if (arr && arr.length > 0) {
    i = arr.length;
    while (i--) {
        element = arr.pop();
        //rest of code
    }
}

answered May 25 '12 at 21:16

T.J. Crowder

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@ElliotBonneville: I haven't. He's not using `i`, he's using `pop`. – T.J. Crowder May 25 '12 at 21:18
You know... I can't remember why I was doing it that way, been a long day. :) Thanks. – Shane May 25 '12 at 21:30

score 1 · Answer 2 · answered Sep 29 '16 at 01:39

1

For future readers, if you're reducing an array's length, don't use a for loop, use a while:

if (arr) {
    while (arr.length) {
        element = arr.pop();
        ...
    }
}

answered Sep 29 '16 at 01:39

Walf

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Cheers... would never do this now... kind of embarrassing to see it up here – Shane Sep 29 '16 at 02:03

score 0 · Answer 3 · answered May 25 '12 at 21:17

0

Yeah--something like this should do the trick:

for (i = arr.length; i > 0; i--) {

answered May 25 '12 at 21:17

Elliot Bonneville

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score 0 · Answer 4 · answered May 27 '12 at 21:11

0

Use jshint rather jslint and turn off the warning.

answered May 27 '12 at 21:11

John

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Closure compiler warning on for loop

4 Answers4