Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.javascript > #21150

Re: (golf-ish) Conditional object property access

Show all headers | View raw

On 2013-09-02 22:23, kj wrote:
> How to shorten the generic JavaScript expression
> 
>     o.hasOwnProperty('p') ? o.p : <EXPR>
> 
> ...while still preserving the *conditional* evaluation of the <EXPR>
> clause?  (Here <EXPR> stands for an arbitrary JavaScript
> expression.)

[...]

> The best that my noob-level JS can come up with is to define a helper
> function `HAS` (in a suitably restricted scope) to replace the verbose
> built-in hasOwnProperty, so that one can at least write:
> 
>     HAS(o, 'p') ? o.p : <EXPR>
> 
> At the end of this post I give other alternatives I could think of,
> but they are all either *more* verbose than what they try to replace,
> or have some other weakness (e.g. failure to delay the evaluation of
> the <EXPR> clause).

I think that's about as close as you can get without special syntactic
sugar. If only the value of truthy properties is of interest, this form
could make a shorter alternative:

    HAS(o, 'p') || <EXPR>

    function HAS (obj, prop)
    {
        if (obj.hasOwnProperty(prop)) {
            return obj[prop];
        }
    }

Golf entertainment aspect aside, is the verbosity of hasOwnProperty()
actually bothering you? This method tends to be used more in libraries
than ad-hoc scripts, so the ugliness should stay well hidden most of the
time.

In a misguided attempt to reduce the download size by increasing the
efficiency of minimizers, I once used something like this (not just for
hasOwnProperty):

    // large library with many occurrences of hasOwnProperty etc:
    (function () {

        var _hasOwnProperty = "hasOwnProperty";

        ...

        if (obj[_hasOwnProperty](prop)) {
           ...

    })();

"_hasOwnProperty" can then be minified/obfuscated to something like "a",
which I thought was a good thing at the time. Honestly, the main effect
was to make the code less readable for the dubious benefit of saving a
few bytes. Not recommended.

I suspect that any highly golfed solution you may discover will suffer
from similar readability problems.

- stefan

Back to comp.lang.javascript | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

(golf-ish) Conditional object property access kj <no.email@please.post> - 2013-09-02 20:23 +0000
  Re: (golf-ish) Conditional object property access Ben Bacarisse <ben.usenet@bsb.me.uk> - 2013-09-02 21:52 +0100
    Re: (golf-ish) Conditional object property access Stefan Weiss <krewecherl@gmail.com> - 2013-09-02 23:11 +0200
    Re: (golf-ish) Conditional object property access Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-09-03 00:03 +0200
      Re: (golf-ish) Conditional object property access Ben Bacarisse <ben.usenet@bsb.me.uk> - 2013-09-02 23:19 +0100
        Re: (golf-ish) Conditional object property access Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-09-03 01:59 +0200
  Re: (golf-ish) Conditional object property access Stefan Weiss <krewecherl@gmail.com> - 2013-09-02 23:10 +0200

csiph-web