Is there a Javascript equivalen of Perl's qw() method to quickly create arrays ? i.e.
in Perl @myarray = qw / one two three /;
in Javascript var myarray = ('one', 'two', 'three' ); // any alternative??
views:
196answers:
3
A:
var array:Array = [ 1 , 2 , 3 ];
var dictionary:Object = { a:1 , b:2 , c:3 };
drawnonward
2010-04-10 04:39:38
it does not compile (in FF at least). I can do var array = [ 1, 2, 3];but not var array = [ one, two, three ].
portoalet
2010-04-10 05:08:57
Quote your strings: `var array = [ 'one', 'two', 'three' ]`
Nikki Erwin Ramirez
2010-04-10 05:58:02
@Nikki I think the point is that he *doesn't* want to quote every single string.
deceze
2010-04-10 06:30:02
In javascript, you have to quote strings unless they are object field names. An array can be initialized with numbers, strings, arrays, or objects.var array:Array = [ 1, "two", [1,2,3], { value:4 }];var dictionary:Object = { one:1, two:"two", three:[1,2,3], four:{value:4}};
drawnonward
2010-04-10 22:58:49
+3
A:
There is not a built in construct, but you can do either of the following:
var myarray = 'one two three'.split(' '); // splits on single spaces
or
function qw (str) {return str.match(/\S+/g)}
var myarray = qw(' one two three '); // extracts words
Eric Strom
2010-04-10 05:53:57
Why `.split(/\s+/)` and not `.split(' ')`? The latter appears to be faster.
Mathias Bynens
2010-04-10 05:57:26
@Mathias => Perl's `qw//` operator will split on variable width whitespace. I've updated my answer to include the faster single char split, and a `qw` clone
Eric Strom
2010-04-10 06:05:28
@Eric: Cool, I didn’t know `qw//` worked like that. Thanks for your explanation!
Mathias Bynens
2010-04-11 07:40:17
+5
A:
To ‘quickly’ write an array, you can do this:
var x = 'foo bar baz'.split(' ');
Especially for large arrays, this is slightly easier to type than:
var x = ['foo', 'bar', 'baz'];
Although obviously, using .split() is much less performant than just writing out the entire array.
Mathias Bynens
2010-04-10 05:56:21
IMHO, the first method is bad form. There's no need to spend unnecessary execution time *every time* the script is ran just to save yourself some key strokes *once*.
Justin Johnson
2010-04-10 07:17:12
IMHO, maintainability and readability trumps an extremely minor increase in execution time.
rjh
2010-04-10 11:37:52
@Justin Johnson: Exactly! That’s why I recommend typing the whole array out instead.
Mathias Bynens
2010-04-11 07:39:04
@rjh What's unmaintainable or unreadable about syntnax as overly common as literal array declaration?
Justin Johnson
2010-04-11 22:19:06
@Justin: a qw()-style function is easier to read and, since IE doesn't support trailing commas in literal array declarations, it's easier to add or remove new items without creating a syntax error. Even if the advantages are minimal, I think this kind of syntax optimisation is pointless unless the construct is inside a tight loop.
rjh
2010-04-18 08:40:09
IMHO, it's silly to consider array literals anything but easy to read, easy to use, and all-around friendly. Also, using array literals is not an optimization, using a qw-style function is pessimization.
Justin Johnson
2010-04-19 09:17:20