Nested return performance

Question

Given these two functions in JavaScript:

function (){
  return _.includes(someLongArray, value) && someSimpleValue;
}

VS

function (){
  return someSimpleValue && _.includes(someLongArray, value);
}

Which of those is going to have better performance? When the someSimpleValue is false, is it going to call the return automatically? Or is it going to verify if the second one is true or false (Useless cause when a && has some of them false it can't be truthy anymore)

score 5 · Accepted Answer · edited May 23 '17 at 12:14

5

The second is more efficient because using the '&&' operator will short-circuit if the first condition evaluates to false.

Further reading/duplicate:

Does JavaScript have "Short-circuit" evaluation?

edited May 23 '17 at 12:14

Community

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answered Aug 03 '15 at 16:24

lintmouse

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Elheni Mokhles · Answer 2 · 2015-08-03T16:28:55.580

2

The second is faster

When using the && operator javascript checks the left side, if it's true checks the right side - if it's false it doesn't check the right side.

As logical expressions are evaluated left to right, they are tested for possible "short-circuit" evaluation using the following rules:

false && (anything) is short-circuit evaluated to false. true || (anything) is short-circuit evaluated to true.

full article

edited Aug 03 '15 at 16:28

answered Aug 03 '15 at 16:26

Elheni Mokhles

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I think you mean the other way around. If the left is false it never evaluates the right. – Mike Cluck Aug 03 '15 at 16:27

score 0 · Answer 3 · answered Jul 26 '17 at 06:13

0

The second one will be faster because of "short-circuit" and as soon as the first condition is false it "exits"

answered Jul 26 '17 at 06:13

Nested return performance

3 Answers3