JavaScript equivalent of ?? operator in C# [duplicate]

Question

Is there any equivalent of ?? operator as exists in C# in JavaScript to defeat 'undefined' checking? For example:

var count = something ?? 0;

var count = (typeof something === 'undefined') ? 0 : something; This is a more verbose version of @Zee's answer (arguably more secure). — evolutionxbox
– evolutionxbox, Commented May 22, 2015 at 10:15
@evolutionxbox: I think you have the values the wrong way around — musefan
– musefan, Commented May 22, 2015 at 10:18

Zee · Accepted Answer · 2015-05-22 10:15:41Z

28

Use logical OR

var count = something || 0;

answered May 22, 2015 at 10:15

Zee

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3 Comments

tigrou Over a year ago

Be aware this will not work with booleans : someflag || true will return true if someflag is false

henon Over a year ago

wouldn't this also fail with an int that is 0 ?

Morvael Over a year ago

Yes, this check will give you bad results with anything on the left side of the operand that could legitimately be falsy. Zero is the obvious problem here, but in this case won't matter. I have been bitten by this so many times i try to avoid using it for anything other than comparing objects now.

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