Javascript RegEx with variable to check for naming format

Question

I have been trying to get a regex working where I can check whether the naming scheme of an ID follows the correct format. But I want to be able to change the format using a variable. The regex combination itself works, but as soon as I tried to add in a variable, it seems to stop functioning. This version seems to work:

const id = $("#div-1-name-1").attr("id");
const regex = new RegExp(/^div-\d-name-\d$/);

console.log(regex.test(id)); // returns true as expected

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
<div id="div-1-name-1"></div>

But as soon as I want to make "name" a variable, so I can interchange this using a function later on, it seems to stop working. For some reason, it always seems to return false.

const id = $("#div-1-name-1").attr("id");
const variableName = "name";
const regex = new RegExp(`/^div-\d-${variableName}-\d$/`);

console.log(regex.test(id)); // returns false, where true expected

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
<div id="div-1-name-1"></div>

Am I perhaps inserting the variable in a wrong way? I cannot seem to figure it out.

``const regex = new RegExp(String.raw`^div-\d-${variableName}-\d$`);`` — Wiktor Stribiżew, Aug 12 '21 at 14:13
Wiktor, if you don’t mind, I’ve added your suggestion as an alternative way for my answer, if you want I can remove it and you can create your own answer — Raz Luvaton, Aug 12 '21 at 14:19

Raz Luvaton · Accepted Answer · 2021-08-13T08:28:16.297

2

You need to escape the regex string and remove the/ from the start and the end like this:

new RegExp(`^div-\\d-${variableName}-\\d$`);

Or as Wiktor commented

new RegExp(String.raw`^div-\d-${variableName}-\d$`);

edited Aug 13 '21 at 08:28

answered Aug 12 '21 at 14:13

Raz Luvaton

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The top method didn't seem to work either for. Tried that earlier before. But the String.Raw apparently does work. Thanks! Also thanks for Wiktor to give this answer. – Abran Aug 13 '21 at 06:47
I updated my answer please try again the top solution – Raz Luvaton Aug 13 '21 at 08:28
That also seems to work, thank you! – Abran Aug 19 '21 at 07:33

Javascript RegEx with variable to check for naming format

1 Answers1