JavaScript String_case Guide
String case conversion: upper, lower, title, and locale-specific case operations for text normalization. The guide walks through Case Methods. `str.toUpperCase()` — all caps. `str.toLowerCase()` — all lower. `str.toLocaleUpperCase("tr")` — locale-aware (Turkish İ/i). Case-insensitive comparison: `a.toLowerCase() === b.toLowerCase()`. For sorting: `a.localeCompare(b, undefined, {sensitivity: "base"})`. CSS: `text-transform: uppercase|lowercase|capitalize`. The guide is organized into 1 sections that build on each other, each pairing a prose explanation with runnable code. Related guides: Arrays, Strings, Numbers, Math, Date. This is one of 145 JavaScript guides on JS Reference — see the full list on the guides page. Practice what you learn in the JavaScript playground, and look up any unfamiliar term in the JavaScript glossary.