Shortest way to write this in javascript?

Question

I'd like to implement this:

//foo is a boolean
if(foo){
    count++;
} else {
    count--;
}

How could I write this with a one liner?

Less code is not always better (unless your sole criterion for "better" is less code, which is not sensible). But in this case one of the offered ternary operations is likely best. — RobG, Apr 27 '12 at 05:28

score 11 · Answer 1 · edited May 23 '17 at 12:21

11

foo ? count++ : count--;

This is called a ternary operator, see Operator precedence with Javascript Ternary operator

Simplest explaination is: if this ? then this : else this

edited May 23 '17 at 12:21

Community

1
1

answered Apr 27 '12 at 04:18

hkf

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In ES5 it's called the *[conditional operator (?:)](http://es5.github.com/#x11.12)*, though it is generlly called a *ternary expression* or *ternary operation* – RobG Apr 27 '12 at 04:47
I like this one because it's both brief and clear and I think it's even easier to read than Nikhil's answer. I personally value clarity over brevity. If you ever spend significant time working on other people's code, you will value the clarity aspect too. – jfriend00 Apr 27 '12 at 04:52

score 9 · Accepted Answer · edited Jun 13 '12 at 12:58

9

Try this:

count += foo ? 1 : -1

edited Jun 13 '12 at 12:58

answered Apr 27 '12 at 04:16

Nikhil Baliga

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KooiInc · Answer 3 · 2012-04-27T05:16:21.367

5

Using short-circuit evaluation and javascripts dynamic typing this should be the shortest:

count += foo || -1;

edited Apr 27 '12 at 05:16

answered Apr 27 '12 at 04:52

KooiInc

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You're assuming that `foo` evaluates to 1, there is no reason to assume that from the OP, what if `foo = 12` or `foo = {…}`? – RobG Apr 27 '12 at 05:26
Citation from the OP: `//foo is a boolean` – KooiInc Apr 27 '12 at 05:38
1

Ok, missed the comment. Still a risky approach though. – RobG Apr 27 '12 at 05:49

score 3 · Answer 4 · answered Apr 27 '12 at 04:17

3

Simplest is to keep the logic you have now and convert to a ternary:

count += foo ? 1 : -1;

answered Apr 27 '12 at 04:17

Andrew

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score 1 · Answer 5 · answered Apr 27 '12 at 04:15

1

You can treat foo as a number, specifically 1 or 0:

count += 2 * foo - 1;

answered Apr 27 '12 at 04:15

Blender

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3

Except this code is completely unreadable... – Travis Webb Apr 27 '12 at 04:28
The OP did ask for the "shortest" way (in the title of the question), not a short answer that was readable. Personally, I find hkf's answer to be the most readable which is probably how I'd do it as I value clarity over brevity (which is the case for anyone who's had to spend a lot of time working/fixing other people's code). – jfriend00 Apr 27 '12 at 04:50

score 0 · Answer 6 · answered Apr 27 '12 at 04:16

0

 count = (foo) ? count+1 : count-1;

answered Apr 27 '12 at 04:16

sgowd

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`count++` and `count--` would make more sense here and then you don't even need the assignment. – jfriend00 Apr 27 '12 at 04:54
Agreed. But any improvement of performance would be there? – sgowd Apr 27 '12 at 05:16

score 0 · Answer 7 · edited Jul 16 '12 at 13:38

0

Please try this:

foo ? count++ : count--;

edited Jul 16 '12 at 13:38

Wouter Dorgelo

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answered Apr 27 '12 at 04:17

sarwar026

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You don't need to assign to `count`. The `count++` and `count--` take care of that already. – jfriend00 Apr 27 '12 at 04:51

Shortest way to write this in javascript?

7 Answers7