fix(isElement): return boolean value rather than truthy value.

[caitp]

angular.isElement currently returns a truthy object/function, or false. This
patch aims to correct this behaviour by casting the result of the isElement
expression to a boolean value via double-negation.

Closes #4519

[mary-poppins]

Thanks for the PR!

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[caitp]

CLA signed previously as Caitlin Potter

[petebacondarwin]

@caitp - Is this change really necessary? I mean if you really want to test for equality you can do

!!isElement(e) === someBooleanValue

But I would expect that the vast majority of the time you would be doing

isElement(e) == someBooleanValue

Especially if you know that someBooleanValue really is definitely a boolean.

[caitp]

@petebacondarwin I tend to agree, it's really just for @gabejohnson and others who want to use the isEqual() / similar strict matchers. You'd have to ask them how big of a deal it is to use strict matchers for boolean-ish expressions.

[jackcviers]

Js non-strict equality is a unpopular practice, because it tends to lie.
The rules surrounding truthiness and falsiness are trivia that's easy to
avoid by using strict equality for the average developer, and the type
coercion rules enfoced by == are the source of lots of small, subtle bugs
in production systems. Keeping Booleans Boolean simplifies matters. There
are settings in jshint to support this option.
On Nov 9, 2013 5:47 PM, "Pete Bacon Darwin" [email protected]
wrote:

@caitp https://github.com/caitp - Is this change really necessary? I
mean if you really want to test for equality you can do

!!isElement(e) === someBooleanValue

But I would expect that the vast majority of the time you would be doing

isElement(e) == someBooleanValue

Especially if you know that someBooleanValue really is definitely a
boolean.

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