I'm using the following javascript to return an array containing the first 2 numerical values found in string

text.match(/(\d+)/g);

How can I stop the search if an open bracket is found and instead return either NaN or zero? For example:

• 10-20 bags (+£1.50) would return 10 and 20
• 20+ bags (+£1.00) would return 20

I'm using the following javascript to return an array containing the first 2 numerical values found in string

text.match(/(\d+)/g);

How can I stop the search if an open bracket is found and instead return either NaN or zero? For example:

• 10-20 bags (+£1.50) would return 10 and 20
• 20+ bags (+£1.00) would return 20

• javascript
• regex

Share Improve this question Follow edited Aug 28, 2014 at 14:06 axelduch 10.9k22 gold badges3333 silver badges5050 bronze badges asked Aug 28, 2014 at 14:03 Nick WNick W 92722 gold badges1616 silver badges3232 bronze badges 1

• If you're trying to match X-Y, then match that, rather than matching both numbers separately. What exactly are you trying to match? There is probably a better solution. – Kendall Frey Commented Aug 28, 2014 at 14:08

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3 Answers 3

Sorted by: Reset to default 3

Use a lookahead in your regex in order to match all the numbers before the first (,

\d+(?=[^()]*\()

Example:

> "10-20 bags (+£1.50)".match(/\d+(?=[^()]*\()/g);
[ '10', '20' ]
> "20+ bags (+£1.00)".match(/\d+(?=[^()]*\()/g);
[ '20' ]

You can use this regex using lookahead:

/(\d+)(?=.*\()/

RegEx Demo

Here (?=.*\() is called lookahead that makes sure match \d+ if it is not followed by an opening (.

If you really need the full generality you requested -- that is, if the lines being matched don't necessarily contain exactly one ( -- then I think the only solution is to first match the lead text before any parenthesis (i.e. /^([^(]*)/) and then select your digit strings from that.

Javascript regexes do not support lookbehind, which is what you need to do the job in the full generality you specified with a single regex.