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Positive look behind in JavaScript regular expression

Answer 1

A:

JavaScript regular expressions do not support lookbehinds. You have to use capturing parenthesis instead:

var str = 'Text:"How secure is my information?"',
    reg = /Text:"([^"]+)"/g;
alert(str.match(reg)[1]);
// -> How secure is my information?

Andy E 2010-08-25 18:35:19

But how do I extract all such data from a large document? Say into an array or something?

Raj 2010-08-25 19:00:53

You use the /g modifier like what I had in my answer.

Crayon Violent 2010-08-25 22:57:26

@Raj: you can use the `/g` modifier, as Crayon Violent said. This is the global modifier, without it the regular expression will stop execution when it finds the first match, with it the regular expression continues until it finds all matches, returning an array with all the matches in it.

Andy E 2010-08-26 08:21:05

Answer 2

+1 A:

string.match(/Text:"([^"]*)"/g)

Crayon Violent 2010-08-25 18:35:31

How to avoid matching Text: in the result?

Raj 2010-08-25 19:30:59

string[0] will always have the full regex match. string[1] will have the captured text. If there was a 2nd capture (parenthesis) in the regex, it would be put in string[2], etc...

Crayon Violent 2010-08-25 19:59:08

I think with /g flag you will only get full regex match for all matches.

Raj 2010-08-25 21:16:17

The g modifier will look for everything on the page that matches, not just stop at the first match. You said you have strings (plural), so that's why I put the /g modifier there.

Crayon Violent 2010-08-25 22:54:58

Answer 3

+2 A:

You can just do:

/Text:"(.*?)"/

Explanation:

Text:" : To be matched literally
.*? : To match anything in non-greedy way
() : To capture the match
" : To match a literal "
/ / : delimiters

codaddict 2010-08-25 18:36:28

How do you use this? Do you have some context?

Sjoerd 2010-08-25 18:39:29

that is the regex, you are supposed to use it with for instance .match()

Crayon Violent 2010-08-25 22:56:53

Answer 4

A:

<script type="text/javascript">
var str = 'Text:"How secure is my information?"';
var obj = eval('({'+str+'})')
console.log(obj.Text);
</script>

Sjoerd 2010-08-25 18:38:46

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Positive look behind in JavaScript regular expression

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