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??
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3 Answers
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.
6 Comments
Justin Johnson
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.
rjh
IMHO, maintainability and readability trumps an extremely minor increase in execution time.
Mathias Bynens
@Justin Johnson: Exactly! That’s why I recommend typing the whole array out instead.
Justin Johnson
@rjh What's unmaintainable or unreadable about syntnax as overly common as literal array declaration?
rjh
@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.
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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
3 Comments
Mathias Bynens
Why
.split(/\s+/) and not .split(' ')? The latter appears to be faster.
Eric Strom
@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 cloneMathias Bynens
Cool, I didn’t know
qw// worked like that. Thanks for your explanation!var array:Array = [ 1 , 2 , 3 ];
var dictionary:Object = { a:1 , b:2 , c:3 };
4 Comments
Lydon Ch
it does not compile (in FF at least). I can do var array = [ 1, 2, 3]; but not var array = [ one, two, three ].
Nikki Erwin Ramirez
Quote your strings:
var array = [ 'one', 'two', 'three' ]
deceze
@Nikki I think the point is that he doesn't want to quote every single string.
drawnonward
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}};