Select character from matched Regex JavaScript

Question

I want to select the character from matched text, but not sure how to do the lookbehind select.

For example, I want to select out the "a" from the "apple" only, and not from "pineapple", I used the regex below:

/\ba(?=pple)/gi

I want to select the "e" from "apple" only, but not sure how to write the regex. The below regex will return the whole word "apple", instead of "e" only.

/\b(appl)e/gi

How can I select out the "e" or any other character such as "l" ?

var text = "apple pineapple aeroplane";

var lookahead = /\ba(?=pple)/gi;
alert(text.match(lookahead));

var lookbehind = /\b(appl)e/gi;
alert(text.match(lookbehind));

/\b(a)pple/ likewise: /\bappl(e)/ if you what's the purpose of Matching Group () Selecting the characters like you do makes me wander what you're actually up to. — Roko C. Buljan
– Roko C. Buljan, Commented Dec 8, 2015 at 4:57
@chris85, I'm trying to not using the matched[2], as I need to have a long regex, and this is part of it only. — Chin
– Chin, Commented Dec 8, 2015 at 6:07

BrunoRB · Accepted Answer · 2015-12-08 04:47:51Z

1

You could do it easily with lookbehind but unfortunately it's not supported by javascript. What you can do instead is to use group capturing and to only retrieve the portion you are insterested in e.g. to capture only "e" of "apple" you could write something like:

var matched = /\bappl(e)/.exec('apple');
var capturedChar = null;
if (matched) {
   // [0] contains the whole matched string, "apple", and [1] contains "e"
   capturedChar = matched[1]; 
}

answered Dec 8, 2015 at 4:47

BrunoRB

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2 Comments

Chin Over a year ago

Actually I need a very long regex that contains multiple conditions, and this is only part of it. So I'm trying not to use matched[1].

BrunoRB Over a year ago

Well, if you could provide a more complete explanation and examples of your situation we would be able to help you better.

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