JavaScript equivalent of ?? operator in C#

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, May 22 '15 at 10:15
@evolutionxbox: I think you have the values the wrong way around — musefan, May 22 '15 at 10:18

score 28 · Accepted Answer · answered May 22 '15 at 10:15

28

Use logical OR

var count = something || 0;

answered May 22 '15 at 10:15

Zee

4

Be aware this will not work with booleans : `someflag || true` will return true if `someflag` is false – tigrou Aug 18 '17 at 15:53
wouldn't this also fail with an int that is 0 ? – henon Mar 19 '18 at 12:52
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. – Morvael Jan 22 '19 at 09:20

1 Answers1