Querying a boolean variable versus comparing two strings in JS

Question

In JavaScript, is there any significant difference in performance between querying a boolean variable's value or testing for the equality of two strings.

For example, which of these, if any, is more efficient:

Boolean example:

var testBoolean = false;

if (testBoolean) {
   alert('false')
}

String example:

var testString = 'false';

if (testString !== 'false') {
   alert('false')
}

Thanks!

Boolean is faster as you have one less comparison to make. You already have test set to false, but in second case you need to do string compare and push the result of that into the IF condition (which is the same as case 1 from here on) — user3991493
– user3991493, Commented Sep 4, 2014 at 16:46
Note that the 2 snippets aren't equivalent. The 1st will fail the if condition. The 2nd will pass and alert(). — Jonathan Lonowski
– Jonathan Lonowski, Commented Sep 4, 2014 at 16:47
Thanks for pointing that out Jonathan, I've now edited the question. — bravokiloecho
– bravokiloecho, Commented Sep 4, 2014 at 16:51

score 1 · Accepted Answer · 2014-09-04 17:02:28Z

1

var testString = 'false';

if (testString === false) {
   alert('I'm inside the if condition')
}

This will never go into the if condition because '===' and '!==' operator check both the value and the type unlike '==' and '!=' operators. But I think that is not your question.

Boolean is faster as you have one less comparison to make. You already have test set to false, but in second case you need to do string compare and push the result of that into the IF condition (which is the same as case 1 from here on)

edited Sep 4, 2014 at 17:02

answered Sep 4, 2014 at 16:50

user3991493

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1 Comment

Jonathan Lonowski Over a year ago

To your 1st point about type, both values are strings. Assuming the use of 'true' as well, the condition could pass.

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