Question

Given this string:

var str = 'A1=B2;C3,D0*E9+F6-';

I would like to retrieve the substring that goes from the beginning of the string up to 'D0*' (excluding), in this case:

'A1=B2;C3,'

I know how to achieve this using the combination of the substr and indexOf methods:

str.substr(0, str.indexOf('D0*'))

Live demo: http://jsfiddle.net/simevidas/XSu22/

However, this is obviously not the best solution since it contains a redundancy (the str name has to be written twice). This redundancy can be avoided by using the match method together with a regular expression that captures the substring:

str.match(/???/)[1]

Which regular expression literal do we have to pass into match to ensure that the correct substring is returned?

My guess is this: /(.*)D0\*/ (and that works), but my experience with regular expressions is rather limited, so I’m going to need a confirmation…

Answer 1

Try this:

/(.*?)D0\*/.exec(str)[1]

Or:

str.match(/(.*?)D0\*/)[1]

DEMO HERE

? directly following a quantifier makes the quantifier non-greedy (makes it match minimum instead of maximum of the interval defined).
Here’s where that’s from