fargo
1a822493ba
963 markdown files reformatted with the repository's pinned prettier so pnpm format:check covers the folded tree like every other repo file. The formatter's embedded-language pass also normalized code fences (TS semicolons, closed HTML tags in examples, lowercased CSS hex colors, one renumbered list that skipped an index). Alphanumeric token deltas vs the fold commit were audited file-by-file; all are formatter-equivalent markup normalizations plus the four sanitized skills.
1.0 KiB
1.0 KiB
title, impact, impactDescription, tags
| title | impact | impactDescription | tags |
|---|---|---|---|
| Hoist RegExp Creation | LOW-MEDIUM | avoids recreation | javascript, regexp, optimization, memoization |
Hoist RegExp Creation
Don't create RegExp inside render. Hoist to module scope or memoize with useMemo().
Incorrect (new RegExp every render):
function Highlighter({ text, query }: Props) {
const regex = new RegExp(`(${query})`, 'gi')
const parts = text.split(regex)
return <>{parts.map((part, i) => ...)}</>
}
Correct (memoize or hoist):
const EMAIL_REGEX = /^[^\s@]+@[^\s@]+\.[^\s@]+$/
function Highlighter({ text, query }: Props) {
const regex = useMemo(
() => new RegExp(`(${escapeRegex(query)})`, 'gi'),
[query]
)
const parts = text.split(regex)
return <>{parts.map((part, i) => ...)}</>
}
Warning (global regex has mutable state):
Global regex (/g) has mutable lastIndex state:
const regex = /foo/g;
regex.test('foo'); // true, lastIndex = 3
regex.test('foo'); // false, lastIndex = 0