| pageClass | sidebarDepth | title | description | since |
|---|---|---|---|---|
rule-details |
0 |
regexp/no-useless-assertions |
disallow assertions that are known to always accept (or reject) |
v0.9.0 |
💼 This rule is enabled in the ✅ plugin:regexp/recommended config.
disallow assertions that are known to always accept (or reject)
Some assertion are unnecessary because the rest of the pattern forces them to always be accept (or reject).
/* eslint regexp/no-useless-assertions: "error" */
/* ✓ GOOD */
var foo = /\bfoo\b/;
/* ✗ BAD */
var foo = /#\bfoo/; // \b will always accept
var foo = /foo\bbar/; // \b will always reject
var foo = /$foo/; // $ will always reject
var foo = /(?=\w)\d+/; // (?=\w) will always acceptRight now, this rule is implemented by only looking a single character ahead and
behind. This is enough to determine whether the builtin assertions (\b, \B,
^, $) trivially reject or accept but it is not enough for all lookarounds.
The algorithm determining the characters ahead and behind is very conservative
which can lead to false negatives.
Nothing.
This rule was taken from eslint-plugin-clean-regex.
This rule is compatible with clean-regex/no-unnecessary-assertions rule.
This rule was introduced in eslint-plugin-regexp v0.9.0