🌐 Frontend & Web

JavaScript's substring(): Quirky, Useful, Utterly Confusing

JavaScript's substring() looks innocent. It bites with swapped args and NaN forgiveness—tripping even vets.

DevTools Feed Apr 03, 2026 3 min read

Read in: Deutsch English Español Français Italiano 日本語 한국어 Português (BR) Русский Türkçe

⚡ Key Takeaways

substring() auto-swaps args and forgives NaN/negatives—handy but hides bugs.
Prefer slice() for negatives and predictability; substring for legacy tolerance.
Always validate indices; JS strings butcher UTF-8 emojis without care.

Published by

Ship faster. Build smarter.

#javascript #slice vs substring #string methods #substring method

Get the best Developer Tools stories of the week in your inbox — no noise, no spam.

Originally reported by dev.to