Using variable inside regex method, can't get it to work

Question

I have read this answer and I understand how to use the Regex constructor and have this this method numerous times before, but in this example I can't understand why the test() method does not return true. Please help! :-)

// This returns true
console.log(/HYD\./gi.test("HYD.,CYLINDER"))

// Now I will use a variable inside this test method so
// I have to use the Regex constructor

const abbreviation = "HYD.";

// I have to replace all "." with "\." to be compliant with the regex language.
const regex = new RegExp(`\\b${abbreviation.replace(".", "\\.")}\\b`, "gi");
console.log(regex)

// Now testing the regex constructor
console.log(regex.test("HYD.,CYLINDER"));

The problem is the second `\b` which doesn't match between the dot and the comma. — georg, Oct 03 '17 at 09:18

score 1 · Answer 1 · answered Oct 03 '17 at 09:19

1

Your two regexes aren't the same. The one you're constructing, with \b "Word Boundary" markers, are causing your regex to fail.

This is because ., is not a word boundary.

Try with a literal /\bHYD\.\b/gi and you'll see it doesn't match either.

answered Oct 03 '17 at 09:19

Niet the Dark Absol

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Ah, sorry! To tired. Thank you! – Isak La Fleur Oct 03 '17 at 09:20

Using variable inside regex method, can't get it to work

1 Answers1