String.prototype.at(index) returns one UTF-16 code unit by index. Positive indexes count from the start; negative indexes count from the end. It is read-only (ES2022) and never mutates the string.
Pass the required arguments shown below. Check return values and browser support before you rely on the result.
Call string.at. Start with this line.
string.at(index)| Call | What it does |
|---|---|
string.at(index) | Primary signature. |
string.at(...) | Call with the arguments your case needs. |
Built into JavaScript. Call at(...) on a string (or String instance) — no import required.
string.at(index)| Parameter | Description |
|---|---|
| index | Required. Position; negative counts from the end |
| Bounds check | Optional. Needed when you must treat a miss specially |
| Return Value | Description |
|---|---|
| * | The value returned by string.at(). |
Read the first and fifth characters with at(0) and at(4).
const text = "CodeToFun";
console.log(text.at(0)); // "C"
console.log(text.at(4)); // "T""CodeToFun" has indexes 0 … 8.at(0) returns "C" — same idea as text[0].at(4) lands on the fifth character → "T".at only reads.Use at(-1) for the last character and at(-2) for the one before it.
const text = "CodeToFun";
console.log(text.at(-1)); // "n"
console.log(text.at(-2)); // "u"length first.-1 + 9 = 8 → "n".-2 + 9 = 7 → "u".text[text.length - 1].at(-1) vs charAt(-1) vs str[-1]Only at() gives clean relative indexing from the end.
const text = "CodeToFun";
console.log(text.at(-1)); // "n"
console.log(JSON.stringify(text.charAt(-1))); // ""
console.log(text[-1]); // undefined
console.log(text[text.length - 1]); // "n"at(-1) resolves to the last character → "n".charAt(-1) returns an empty string "".text[-1] means property "-1", which does not exist → undefined.at(-1), never str[-1] or charAt(-1).String.prototype.at() is part of ES2022. Evergreen browsers shipped it in 2021–2022; Node.js added it in version 16.6.
Supported in Chrome 92+, Firefox 90+, Safari 15.4+, Edge 92+, and Node 16.6+. Not available in Internet Explorer.
Bottom line: Safe for modern web apps and current Node LTS releases. For IE11 or very old browsers, feature-detect with if ("at" in String.prototype) and fall back to str[str.length - 1] or charAt(str.length - 1).
Compare the classic index method that returns an empty string instead of undefined.
9 people found this page helpful