ASCII 7 bell character in in JavaScript's regular expressions

Question

How do I make a ASCII 7 bell character in JavaScript's regular expressions?

My regex: ^[#&][^ \a]{0,200}$

The regex above causes literally to not take the character a instead of the ASCII 7 character.

Even at the explanation on the right side of Regex101 it says:

\a matches the bell character (ASCII 7)

Javascript doesn't support the `\a` in regex, you'd have to use `\u2407` instead — adeneo, Nov 16 '16 at 20:57

score 3 · Answer 1 · edited May 23 '17 at 10:30

3

You cannot write "\a" and expect a bell char in the string as JS escape sequences do not include this one.

However, to find it in the text, use /\x07/:

console.log(/\x07/.test("\x07"));

Another possible issue is that you are trying to match a Unicode ␇ char, then see Target a bell character with a regular expression.

edited May 23 '17 at 10:30

Community

answered Nov 16 '16 at 21:01

Wiktor Stribiżew

1

As a side note, **do not believe everything regex101.com tells you**, check the documentation and test your regexps in the target environment - always. Regex101 still has bugs. – Wiktor Stribiżew Nov 16 '16 at 21:03
I have a related question about non-printable control characters here: https://stackoverflow.com/questions/73633022/what-is-the-purpose-of-non-printable-control-characters-in-this-email-validation. I think user6410654 question and your answer here are helpful in getting to the bottom of it. Thank you! I observe that if I `console.log('\x07');` in node.js running in the macOS terminal, the computer makes a beeping sound. – jamesmortensen Sep 27 '22 at 09:12

adeneo · Accepted Answer · 2016-11-16T21:09:04.970

0

According to MDN, the \a modifier is not on the list of supported modifiers for regular expressions in Javascript.

If you want to match the ␇ symbol you can use \u2407

console.log( "Test␇String".match(/\u2407/) )

If you want to match the bell character  you'd use \u0007

var s = document.getElementById('test').innerHTML;
console.log( s.match(/\u0007/) )

<div id="test">&#7;test</div>

edited Nov 16 '16 at 21:09

answered Nov 16 '16 at 21:03

adeneo

2 Answers2