JavaScript check if string contains any of the words from regex

Question

I'm trying to check if a string contains any of these words:

AB|AG|AS|Ltd|KB|University

My current code:

var acceptedwords = '/AB|AG|AS|Ltd|KB|University/g'
var str = 'Hello AB';

var matchAccepted = str.match(acceptedwords);
console.log(matchAccepted);

if (matchAccepted !== null) { // Contains the accepted word
    console.log("Contains accepted word: " + str);          

} else {
    console.log("Does not contain accepted word: " + str);

}

But for some strange reason this does not match.

Any ideas what I'm doing wrong?

new RegExp('AB|AG|AS|Ltd|KB|University', 'g') or /AB|AG|AS|Ltd|KB|University/g but not a combination of the two :) — Ja͢ck
– Ja͢ck, Commented Jun 11, 2014 at 7:06

Community · Accepted Answer · 2017-05-23 12:03:05Z

21

That's not the right way to define a literal regular expression in Javascript.

Change

var acceptedwords = '/AB|AG|AS|Ltd|KB|University/g'

to

var acceptedwords = /AB|AG|AS|Ltd|KB|University/;

You might notice I removed the g flag : it's useless as you only want to know if there's one match, you don't want to get them all. You don't even have to use match here, you could use test :

var str = 'Hello AB';
if (/AB|AG|AS|Ltd|KB|University/.test(str)) { // Contains the accepted word
    console.log("Contains accepted word: " + str);          
} else {
    console.log("Does not contain accepted word: " + str);
}

If you want to build a regex with strings, assuming none of them contains any special character, you could do

var words = ['AB','AG', ...
var regex = new RegExp(words.join('|'));

If your names may contain special characters, you'll have to use a function to escape them.

If you want your words to not be parts of other words (meaning you don't want to match "ABC") then you should check for words boundaries :

regex = new RegExp(words.map(function(w){ return '\\b'+w+'\\b' }).join('|'),'g');

edited May 23, 2017 at 12:03

CommunityBot

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answered Jun 11, 2014 at 7:04

Denys Séguret

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6 Comments

Alosyius Over a year ago

could I somehow insert a string between / myVarHere / g ?

h2ooooooo Over a year ago

@Alosyius See the var regex = RegExp('AB|AG|AS|Ltd|KB|University', 'g'); constructor.

Felix Kling Over a year ago

@Alosyius: [javascript] variable in regex

Alosyius Over a year ago

Awesome! Accepting asap :)

garyh Over a year ago

@dystroy Would the accepted words not need to be surrounded by word boundaries, \b otherwise you could get matches when the accepted words appear within other words. See here: regex101.com/r/zS8dT9

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