feat(lint): add new js lint: useTopLevelRegex

[dyc3]

Summary

This rule detects regex literals that are defined inside functions. This can result in performance problems if a function like this is called often:

function foo(someString) {
	return /[a-Z]*/.test(someString)
}

Instead, biome will now encourage users to place regex literals at the top level of a module.

const REGEX = /[a-Z]*/;

function foo(someString) {
	return REGEX.test(someString)
}

It's a little unclear to me if it would be preferable to implement this using a Visitor instead.

closes #2148

Test Plan

Added snapshot tests

cargo test -p biome_js_analyze use_top_level_regex

[codspeed-hq]

CodSpeed Performance Report

Merging #2794 will not alter performance

_{Comparing dyc3:05-09-feat_lint_add_new_js_lint_usetoplevelregex_ (c13ff04) with main (9c920a1)}

Summary

✅ 99 untouched benchmarks

[Conaclos]

Calling test/exec have side effects when a regex is set with the y and/or g flag. I think we should ignore regexes if one of its flags is set.

[dyc3]

Currently, we don't parse the regex expression and flags as separate syntax nodes, so resolving that would require either string parsing (which is probably an antipattern here) or updating the grammar and to add those nodes. I think that would be better to put in a separate PR or 2. I can open issues for those once this is merged.

[Conaclos]

Currently, we don't parse the regex expression and flags as separate syntax nodes, so resolving that would require either string parsing (which is probably an antipattern here) or updating the grammar and to add those nodes. I think that would be better to put in a separate PR or 2. I can open issues for those once this is merged.

I remembered that we have a utility for that: you can call decompose() on a JsRegexLiteralExpression. This will return a pair that contains the regex and its flags.

[dyc3]

Ah, I see, thanks for pointing that out. I could go ahead and do that in this PR if you like, but I would rather get this merged as is so that I don't have to keep rebasing this branch.

[dyc3]

For the record, do we want to update the grammar to add a node for the regex flags?

[Conaclos]

For the record, do we want to update the grammar to add a node for the regex flags?

I don't think so.
However, we could implement a parser for regex literals.
Regex could be parsed using a Visitor. Only rule requiring the parsed form of regex literals could subscribe to the visitor.