Regex Cheat Sheet for JavaScript Developers

Use ^ and $ for anchors, . for any character except newline, \d for digits, \w for word characters, [] for character classes, () for groups, | for alternatives, and ? + * {n,m} for quantifiers.

Prefer smaller patterns that are easy to test. When a pattern becomes hard to explain, split validation into parsing plus simple checks.

Forgetting flags, overusing greedy quantifiers, trying to parse HTML with regex, and treating email validation as a one-line universal truth all create fragile results.