String.prototype.at()

at(index)

Returns: string | undefined · Added in vES2022 · Updated March 13, 2026 · String Methods

javascript es2022 string character negative-index

The at() method returns the character at the specified index in a string. Its standout feature is support for negative indices, which count backward from the end—this makes it the preferred method when you need to access characters relative to a string’s end.

Syntax

string.at(index)

index: An integer representing the position of the character. Positive indices count from the start (0-indexed), negative indices count from the end.
Returns: A string containing the character at the specified index, or undefined if the index is out of bounds.

TypeScript Signature

interface String {
  at(index: number): string | undefined;
}

Basic Character Retrieval

const text = "Hello";

console.log(text.at(0)); // "H"
console.log(text.at(1)); // "e"
console.log(text.at(4)); // "o"

Negative Indices (Index-from-End)

This is where at() shines. Use negative indices to access characters counting backward from the end:

const filename = "document.pdf";

console.log(filename.at(-1)); // "f" (last character)
console.log(filename.at(-2)); // "f"
console.log(filename.at(-3)); // "."
console.log(filename.at(-4)); // "d"

at() vs charAt() vs Bracket Notation

Here’s how at() compares to the alternatives:

const text = "Hi";

// at(): supports negative indices, returns undefined for out-of-bounds
console.log(text.at(0));    // "H"
console.log(text.at(-1));   // "i" (negative works!)
console.log(text.at(5));    // undefined

// charAt(): no negative index support, returns empty string for out-of-bounds
console.log(text.charAt(0));  // "H"
console.log(text.charAt(-1)); // "" (negative becomes 0)
console.log(text.charAt(5));  // "" (empty string)

// bracket notation: no negative index support, returns undefined
console.log(text[0]);       // "H"
console.log(text[-1]);      // undefined (no negative support)
console.log(text[5]);       // undefined

The key differences:

at(): Supports negative indices, returns undefined for out-of-bounds
charAt(): No negative indices, returns empty string "" for out-of-bounds
Bracket notation: No negative indices, returns undefined for out-of-bounds

Out of Bounds Behavior

When the index exceeds the string’s length or is otherwise invalid, at() returns undefined rather than an empty string:

const text = "test";

console.log(text.at(10));     // undefined
console.log(text.at(-10));    // undefined (too far from end)
console.log(text.at());       // undefined (index becomes NaN → 0)

This undefined return is useful—it clearly signals “no character found” rather than returning an empty string that might go unnoticed.

Browser Compatibility

Browser	Version
Chrome	92+
Firefox	90+
Safari	16.4+
Edge	92+
Node.js	16.6.0+

Added in ES2022. Not supported in older browsers—use a polyfill or fall back to charAt() when needed.