@rbxts/jsnatives

at

Returns the character at a specified index in a string.

Signature

function at(str: string, index: NumericAdmissible): string

Description

The at function returns the character at a specified position in a string. This method allows for both positive and negative integers, where negative integers count back from the end of the string.

Parameters

str: The string to extract a character from.
index: The position of the character to get. If a string is provided, it will be converted to a number.

Return value

A string containing a single character at the specified index.
An empty string if the index is out of range.

Examples

Basic usage

// Get a character by index
const char = String.at("Hello", 1);
print(char); // Outputs: "e"

const firstChar = String.at("Hello", 0);
print(firstChar); // Outputs: "H"

Using negative indices

// Negative indices count from the end of the string
const str = "Hello";
const lastChar = String.at(str, -1);
print(lastChar); // Outputs: "o"

const secondToLast = String.at(str, -2);
print(secondToLast); // Outputs: "l"

Using string indices

// String indices are converted to numbers
const str = "Hello";
const char = String.at(str, "2");
print(char); // Outputs: "l"

Handling out of range indices

const str = "Hello";

// Index beyond the string length
const outOfRange = String.at(str, 10);
print(outOfRange); // Outputs: "" (empty string)

// Negative index beyond start of string
const tooNegative = String.at(str, -10);
print(tooNegative); // Outputs: "" (empty string)

Common use cases

// Get first character
function getFirstChar(str: string): string {
  return String.at(str, 0);
}
print(getFirstChar("Hello")); // Outputs: "H"

// Get last character
function getLastChar(str: string): string {
  return String.at(str, -1);
}
print(getLastChar("Hello")); // Outputs: "o"

// Safely get character at index
function safeCharAt(str: string, index: number): string | undefined {
  const char = String.at(str, index);
  return char !== "" ? char : undefined;
}