Using regex to extract strings given a pattern in JavaScript

Question

I'm trying to figure out how to grab only the values in between known begin and end strings. For example, using this string:

I need [?Count?] [?Widgets?]

I need the the values Count and Widgets returned.

I tried

[?(.*)?]

and ended up with

I need [
Count
] [
Widgets
]

Is there a way, using these begin and end strings, to parse out the values I need? Or should I try and find a way to change them before parsing out the values? I really appreciate any help you can provide.

Thank you!

Ben Lee · Answer 1 · 2011-10-10 23:51:42Z

var str = "I need [?Count?] [?Widgets?]";
$(str.match(/\[\?.*?\?\]/g)).map(function(i) { return this.match(/\[\?(.*)\?\]/)[1] });
// => ['Count'], 'Widgets']

Note that in the regex, you have to escape [, ], and ? as they are special characters. Also use the g flag at the end of the regex to find all matches. I'm also using .*? instead of .* -- that means non-greedy match or "find the shortest possible match", which is what you want here.

Finally, the results are mapped (using jquery map) to remove the '[?' and '?]' from the results.

Or, if you don't want the special characters removed, don't even use the map:

var str = "I need [?Count?] [?Widgets?]";
str.match(/\[\?.*?\?\]/g);
// => ['[?Count?]'], '[?Widgets?]']

Thank you Ben. Using those characters probably wasn't the best. Your function works great. I really appreciate your help :)

verybadbug · Answer 2 · 2011-10-10 23:46:55Z

up vote 1 down vote

In your regular expression try \[\?([^\?]*)\?\]

answered Oct 10 '11 at 23:46

verybadbug
8413

	Note that instead of `[^\?]` you can just do `.?`: The latter means "match the shortest possible match", which in this case will be everything up until the first "?]" it finds, but nothing more. – Ben Lee Oct 10 '11 at 23:52
	I knows this is lazy alg, but my expression works too ))) – verybadbug Oct 10 '11 at 23:59
	Thanks verybadbug. In using Ben's str above, I tried this: var p = str.match([\?([^\?]*)\?]); but can't get it to work because of the syntax. Am I missing something obvious? thank you. – DrZ Oct 11 '11 at 0:07
	missing backslash for first and last brackets – verybadbug Nov 2 '11 at 12:13

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Using regex to extract strings given a pattern in JavaScript

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