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From: Richard Cornford on 5 May 2008 19:26
Zack wrote:
> Hi,
>
> Let's say you have this function named validate. validate looks
> like this:
>
> function validate() {
> return ($F("Email") != '' ? ($("Name").value = $F("Email")) :
> false);
> }
>
> (Using prototype.js. For those not familiar $() is like
> getElementById and $F is like getElementById().value for form
> elements) There's a lot happening on this 1 line so let's break
> it down.
>
> If the value of element "Email" is not empty string, return the
> result of setting value of element "Name" = the value of
> element "Email", otherwise return false.
>
> This works exactly as I want it too, but is it OK? By OK I mean
> good javascript style? There's something fishy smelling to me
> about doing any sort of assignment in the expression part of
> the conditional.

There is an often expressed style opinion that code that produces side
effects should not appear in the expressions of a conditional operation;
that under those circumstances an - if/else - block would be more
appropriate, and make the side effect easier to observe. The assignment
to the 'Name' field probably qualifies as a side effect in this case.
One branch of responses to this thread seems to suggest that the
side-effect in the conditional expression was not as apparent as it
should be.

However, in any programming language it would be considered bad style to
be disregarding a language usage convention that appears in the
language's specification, and as Prototype.js disregards ECMA 262 (all
versions)'s injunction against using the $ symbol as the first character
in any Identifier that is not machine generated if you are using
Prototype.js it is already too late to be worrying about 'good style'.

<snip>
> But it's just not as cool looking. ...

Programming is an activity where producing 'cool looking code' is never
going to be a reason for doing anything. If 'cool looking' is a side
effect of doing the right thing then so be it, otherwise it is a mistake
to be doing anything but the right thing.

Richard.

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