Question

My web application needs to parse numeric ranges in strings that are enclosed by parenthesis. I’ve never really understood regex properly so I need some assistance. The code below is kind of what I’m looking to do (I’ll then split the string on the hyphen and get the min/max values). Obviously the pattern is wrong – the example below alerts “(10-12) foo (5-10) bar” when my desired result is 1 alert saying (10-12) and the next saying (5-10), or better yet those values without the parenthesis if that’s possible.

Any assistance is appreciated.

var string = "foo bar (10-12) foo (5-10) bar";
var pattern = /\(.+\)/gi;
matches = string.match(pattern);

for (var i in matches) {
    alert(matches[i]);
}

Answer 1

Make your quantifier lazy by adding a ? after the +. Otherwise, it will greedily consume as much as possible, from your opening ( to the last ) in the string.

var string = "foo bar (10-12) foo (5-10) bar",
    pattern = /\(.+?\)/g,
    matches = string.match(pattern);

jsFiddle.

If you don’t want to include the parenthesis in your matches, generally you’d use a positive lookahead and lookbehind for parenthesis. JavaScript doesn’t support lookbehinds (though you can fake them). So, use…

var string = "foo bar (10-12) foo (5-10) bar",
    pattern = /\((.+?)\)/g,
    match,
    matches = [];

while (match = pattern.exec(string)) {
    matches.push(match[1]);
}

jsFiddle.

Also…

• You don’t need the i flag in your regex; you don’t match any letters.
• You should always scope your variables with var. In your example, matches will be global.
• You shouldn’t use a for (in) to iterate over an array. You should also check that match() doesn’t return null (if no results were found).