Is it safe to use || instead of if? - JavaScript

Question

Recently, I have noticed, that putting an or operator between two functions, will make the second one run only if the first side of the operator is false. Is it safe to use this instead of if statements?

Example:

function a(){ return Math.random() >= 0.5; } 
function b(){ console.log("foo"); }

Using

!a() || b();

has the same behaviour as

if( a() ) b();

My question is: Is it safe to use this syntax? Are there exceptions?

There isn't anything wrong with it logically or syntactically, you may lose readability or introduce confusion in some cases. — Steve Buzonas, Jul 25 '14 at 22:00
`a() && b()` is probably better :P and *very* slightly more readable — Populus, Jul 25 '14 at 22:01

score 8 · Accepted Answer · edited May 23 '17 at 12:20

8

Yes, it is safe to rely on this (although the readability is open to debate and depends on the exact use case).

This behaviour is called "short-circuit evaluation", and is a feature of many programming languages. See Does JavaScript have "Short-circuit" evaluation?

edited May 23 '17 at 12:20

Community

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answered Jul 25 '14 at 21:59

NPE

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Is it safe to use || instead of if? - JavaScript

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