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Javascript – Regex to match words on specific lines

Given the following example from a class definition in ObjectScript:

Include %sySystem
Include (%sySystem, %soap, %Net.WebSocket)

Class HS.Local.zimpl.fhirpro.UI.FileViewer Extends (HS.Local.zimpl.fhirpro.UI.Super, %CSP.Page)

I need to match the individual words behind "Include" and the pattern must not match on any other line. Matches must exclude any punctuation.

The regex will be used in Javascript.

My best efforts produced this:

(?<=^Include (?)([%A-Za-z0-9.]+)|((?<=, )[%A-Za-z0-9.]+)

A positive lookbehind finds lines starting with "Include " and optionally an opening parenthesis, matching words which may contain a percent symbol or period.

In order to match further words I added the alternative OR and a second capturing group with a further lookbehind. This results in many other lines being matched though – essentially anything behind a comma and space.

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2

Answers


  1. 0

    You can use the following regex to achieve the same:

    (?<=^Includes+(?)([%A-Za-z0-9]+)|(?<=,s)([%A-Za-z0-9]+)

    const regex = /(?<=^Includes+(?)([%A-Za-z0-9]+)|(?<=,s)([%A-Za-z0-9]+)/g;
const str = `Include %sySystem`;

const matches = str.match(regex);

console.log({matches})
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  2. 0

    The (?<=^Include (?) lookbehind only applies to the first alternative in your regex pattern.

    To make it apply to any "word" that matches your main [%A-Za-z0-9.]+ pattern you need to add .* inside it:

    /(?<=^Include .*)[%A-Za-z0-9.]+/gm
/(?<=^Include .*)[%a-z0-9.]+/gmi

    See the regex demo. I removed )? from the lookbehind because .* matches a ) symbol, too.

    Note that if the "words" always start with %, you may use %[A-Za-z0-9.]+ instead of [%A-Za-z0-9.]+.

    More details:

    • (?<=^Include .*) – a positive lookbehind that matches a location that is immediately preceded with Include at the start of the line (if you remove m flag, then only the start of the whole string) and then followed with a space and any zero or more chars other than line break chars after it
    • [%A-Za-z0-9.]+ – one or more ASCII letters, digits, and . and % chars.
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