Pattern: Not strictly valid regular expression pattern
Issue: -
This rule disallows not strictly valid regular expressions.
An invalid pattern in a regular expression literal is a SyntaxError when the code is parsed. However, it is not always strictly checked.
Depending on the syntax defined in Annex B of the ECMAScript specification, some ambiguous pattern syntax may also succeed in parsing as a valid pattern. This rule reports these ambiguous patterns.
/* eslint regexp/strict: "error" */
/* ✓ GOOD */
var foo = /\}/
var foo = /\{/
var foo = /\]/
var foo = /\u{42}/u; // It matches "B"
var foo = /u{42}/; // It matches a string followed by 42 "u"s
/* ✗ BAD */
var foo = /}/
var foo = /{/
var foo = /]/
var foo = /\u{42}/; // It matches a string followed by 42 "u"s