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String.prototype.at()

main Documentación oficial Licencia CC-BY-SA-2.5Descargado el 2026-08-02

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The at() method of {{jsxref("String")}} values takes an integer value and returns a new {{jsxref("String")}} consisting of the single UTF-16 code unit located at the specified offset. This method allows for positive and negative integers. Negative integers count back from the last string character.

{{InteractiveExample("JavaScript Demo: String.prototype.at()")}}

```js interactive-example const sentence = "The quick brown fox jumps over the lazy dog.";

let index = 5;

console.log(An index of ${index} returns the character ${sentence.at(index)}); // Expected output: "An index of 5 returns the character u"

index = -4;

console.log(An index of ${index} returns the character ${sentence.at(index)}); // Expected output: "An index of -4 returns the character d"

## Syntax

```js-nolint
at(index)

Parameters#

  • index
  • : The index (position) of the string character to be returned. Supports relative indexing from the end of the string when passed a negative index; i.e., if a negative number is used, the character returned will be found by counting back from the end of the string.

Return value#

A {{jsxref("String")}} consisting of the single UTF-16 code unit located at the specified position. Returns {{jsxref("undefined")}} if the given index can not be found.

Examples#

Return the last character of a string#

The following example provides a function which returns the last character found in a specified string.

// A function which returns the last character of a given string
function returnLast(str) {
  return str.at(-1);
}

let invoiceRef = "my-invoice01";

console.log(returnLast(invoiceRef)); // '1'

invoiceRef = "my-invoice02";

console.log(returnLast(invoiceRef)); // '2'

Comparing methods#

Here we compare different ways to select the penultimate (last but one) character of a {{jsxref("String")}}. While all below methods are valid, it highlights the succinctness and readability of the at() method.

const myString = "Every green bus drives fast.";

// Using length property and charAt() method
const lengthWay = myString.charAt(myString.length - 2);
console.log(lengthWay); // 't'

// Using slice() method
const sliceWay = myString.slice(-2, -1);
console.log(sliceWay); // 't'

// Using at() method
const atWay = myString.at(-2);
console.log(atWay); // 't'

Specifications#

{{Specifications}}

Browser compatibility#

{{Compat}}

See also#