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milliams | karma 2525 | avg karma 5.33 · 2013-10-15 12:56:52+00:00

Does JavaScript not have something like "bool(value)"?

benjoffe | karma 642 | avg karma 4.04 · 2013-10-15 13:02:09

You can use Boolean(value) but it will return an 'object' of a 'boolean' type, rather than a primitive boolean (it's one of JS's flaws so is generally avoided).

Note: their example of a similar piece of code is not identical, as it won't cast values like null to false. I think the best example of a clear equivalent would be:

    value = value ? true : false;

gsnedders | karma 6022 | avg karma 2.57 · 2013-10-15 13:05:49+00:00

`Boolean(value)` returns a boolean primitive; `new Boolean(value)` returns a boolean object (which you never want).

Compare:

    > typeof Boolean(1)
    'boolean'
    > typeof new Boolean(1)
    'object'

Guillaume86 | karma 554 | avg karma 1.59 · 2013-10-15 13:10:41+00:00

In chrome console I get an object for new Boolean(false) but I think it is the primitive for Boolean(false), am I right or I missed something?

onestone | karma 1885 | avg karma 10.3 · 2013-10-15 13:28:17

The !! mentioned in the article does exactly that.