prefer-predefined-assertion.md

Pattern: Lookaround used where predefined assertion exists

Issue: -

Description

All predefined assertions (\b, \B, ^, and $) can be expressed as lookaheads and lookbehinds. E.g. /a$/ is the same as /a(?![^])/.

In most cases, it's better to use the predefined assertions because they are better known.

Examples

/* eslint regexp/prefer-predefined-assertion: "error" */

/* ✓ GOOD */
var foo = /a(?=\W)/;

/* ✗ BAD */
var foo = /a(?![^])/;
var foo = /a(?!\w)/;
var foo = /a+(?!\w)(?:\s|bc+)+/;