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String Prototype Methods

slice() and at() accept negative indexes counted from the end; substring() treats them as 0. Avoid the deprecated substr() and HTML wrappers such as bold(). Normalize input before comparing: é can be one code point or two.

String prototype methods by purpose
Purpose Methods
Search includes, startsWith, endsWith, indexOf, lastIndexOf, search
Extract at (ES2022), charAt, slice, substring, split
Unicode charCodeAt, codePointAt, normalize, isWellFormed, toWellFormed (ES2024)
Transform toUpperCase, toLowerCase, toLocale...Case, repeat, concat
Trim and pad trim, trimStart, trimEnd, padStart, padEnd
Regular expressions match, matchAll, replace, replaceAll (Regular Expressions)
Everyday string methodsJavaScriptLive
const t = '  Hello, World  '.trim();
console.log(t.at(-1), t.slice(-5, -1), t.indexOf('o'), t.lastIndexOf('o'), t.includes('World'));
console.log(t.split(', '), t.replaceAll('l', 'L'), t.padStart(15, '*'), 'ab'.repeat(3));
console.log('caf\u00e9' === 'cafe\u0301', 'caf\u00e9' === 'cafe\u0301'.normalize('NFC'));