Coworker had me grep for the string "true : false" through our project, and I found a lot of ternary operators returning explicit true or false. For example:
return this.state == Cursor.CLOSED ? true : false;
Not just in our project, but plenty of modules/libraries do this. It seems redundant to me, since the author could have just written it like this:
return this.state == Cursor.CLOSED;
Is it defensive coding against some gotcha in Javascript? Or just to be explicit with what you are returning?
Coworker had me grep for the string "true : false" through our project, and I found a lot of ternary operators returning explicit true or false. For example:
return this.state == Cursor.CLOSED ? true : false;
Not just in our project, but plenty of modules/libraries do this. It seems redundant to me, since the author could have just written it like this:
return this.state == Cursor.CLOSED;
Is it defensive coding against some gotcha in Javascript? Or just to be explicit with what you are returning?
Share Improve this question edited Jun 12, 2014 at 15:56 p.s.w.g 149k31 gold badges304 silver badges336 bronze badges asked Jun 12, 2014 at 15:50 Ross HettelRoss Hettel 1,1291 gold badge9 silver badges19 bronze badges 12- 3 that seems to simply return true if the state is closed? What's wrong with that? Your question is very unclear. – Liam Commented Jun 12, 2014 at 15:52
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I think he's asking that it could just be
return this.state == Cursor.CLOSED;– Vic Commented Jun 12, 2014 at 15:54 -
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To me it seems uneccessary, if
this.state == Cursor.CLOSEDit's already true ? – adeneo Commented Jun 12, 2014 at 15:54 -
In this case, I'd guess the author didn't realize that he / she could just return the result of the parison. However,
return foo || bar ? true : false;is very different from justreturn foo || bar. – p.s.w.g Commented Jun 12, 2014 at 15:54 -
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@RossHettel: In that case, it's being used as a more prominent version of
!!. The value wasn't already a boolean —String.prototype.matchreturns an array. – Chuck Commented Jun 12, 2014 at 16:11
2 Answers
Reset to default 11Is it defensive coding against some gotcha in Javascript?
No. == does always return a boolean value.
The conditional is pletely redundant, and considered a bad practise. Simplify it!
It's quite unnecessary, but it's a pretty mon mistake† in many languages. Because the equality operator is used almost exclusively in conditions, some less-knowledgeable programmers don't know and more experienced programmers occasionally forget that it can actually be used for its value. There has never been any major JavaScript implementation that had a quirk that made this necessary.
† "Mistake" feels unkind here, since the code is correct, just needlessly verbose. But I think you know what I mean.