In Javascript, how to explain 0 == "" returning true?

Asked Oct 02 '11 at 15:45

Active Oct 02 '11 at 15:45

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Possible Duplicate:
Why is 0 == “” true in JavaScript

The following is done in Firebug:

>>> 0 == ""
true

>>> "" == false
true

But how did the "" get converted to 0? I think the reason they both returned true was that "" gets converted to 0, and in the first case, it becames 0 == 0, and in the second case, first to "" == 0 and then 0 == 0 and so both cases returned true, but how did "" get converted into 0? The Javascript Definitive Guide says the string is converted to a number, but how specifically?

edited May 23 '17 at 12:03

Community

asked Oct 02 '11 at 15:45

nonopolarity

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They're both "falsy" values. `0` is evaluated as `false` and so is the empty string: `""`. – Kevin Oct 02 '11 at 15:47
Both `""` and `0` are `falsy` values. What you're looking for is the **strict equaliance** operator `===`, which of course return `false`. – user278064 Oct 02 '11 at 15:47
1

Javascript doesn't work like that -- both `2` and `true` are "truthy" but `2 == true` will return `false` (but `1 == true` will return `true` so that can make you go crazy) – nonopolarity Oct 02 '11 at 15:50
http://es5.github.com/#x11.9.3 – NullUserException Oct 02 '11 at 15:53
And http://es5.github.com/#x9.3 – Felix Kling Oct 02 '11 at 16:00
The important thing in the specs is: `The MV of StringNumericLiteral ::: [empty] is 0`. – pimvdb Oct 02 '11 at 16:04

In Javascript, how to explain 0 == "" returning true?

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