no-invalid-regexp

A mistake in a regular expression literal is a syntax error, so you see it right away. A pattern passed to RegExp as a string is only checked when that line runs, and then it throws a SyntaxError. This rule checks the string ahead of time.

Only string literals are checked. If the pattern or the flags come from a variable, that part is skipped.

This rule is on by default.

Configure

On by default as an error. To turn it off:

[lint.rules]
"no-invalid-regexp" = "off" # or "warn"

Every option, set to its default:

[lint.rules]
"no-invalid-regexp" = ["error", {
  allowConstructorFlags = [], # list of strings
}]

Examples

Reported:

const letters = new RegExp("[a-z");
const digits = RegExp("(\\d+");
const twice = new RegExp("\\d+", "gg");
const unknown = new RegExp("\\d+", "x");

Not reported:

const letters = new RegExp("[a-z]");
const digits = RegExp("(\\d+)", "g");
const search = new RegExp(pattern, flags);

Options

Option	Default	What it does
allowConstructorFlags	[]	Extra flags to accept, one letter each, for a runtime that supports flags the standard doesn't have. Case matters.

const digits = new RegExp("\\d+", "x");

const digits = new RegExp("\\d+", "X");