String Basics: length, charAt(), at()

Syntax

str.length
str.charAt(index)
str.at(index)

Examples

const text = "Hello";

console.log(text.length);     // 5
console.log(text.charAt(0));  // "H"
console.log(text[1]);         // "e" - bracket access also works
console.log(text.charAt(10)); // "" - out of range returns empty string

const text = "JavaScript";

console.log(text.at(0));  // "J"
console.log(text.at(-1)); // "t" - last character
console.log(text.at(-2)); // "p" - second to last

// Compare with charAt(), which has no negative index support
console.log(text.charAt(text.length - 1)); // "t" - more verbose equivalent

Best practices

• Use at(-1) instead of str[str.length - 1] for cleaner access to the last character
• Remember strings are immutable - "changing" a character actually means creating an entirely new string
• Use bracket notation (str[0]) or charAt() interchangeably for simple positive-index access - both work identically for valid indices
• Check .length before accessing indices in a loop to avoid undefined results from out-of-range access

At a glance

Purpose

Application logic and interaction

File extension

.js · .mjs

Runs in

Browsers and JavaScript runtimes

Usually used with

HTML, CSS and Web APIs

Specifications & further reading

• ECMAScript specification

Related JavaScript documentation