@rbxts/jsnatives

charCodeAt

Returns the Unicode value of the character at the specified position in a string.

Signature

function charCodeAt(str: string, index: number | string): number

Description

The charCodeAt function returns an integer representing the Unicode value of the character at the specified position in a string. from the UTF-8 code unit.

Parameters

str: The string to extract a character code from.
index: The zero-based index of the character. If a string is provided, it will be converted to a number.

Return value

A number representing the UTF-8 code unit at the specified index.
If the index is out of range, it returns NaN.

Examples

Basic usage

// Get the character code of 'A'
const code = String.charCodeAt("ABCDE", 0);
print(code); // Outputs: 65

// Get the character code of 'C'
const middleCode = String.charCodeAt("ABCDE", 2);
print(middleCode); // Outputs: 67

Using with string index

// String indices are automatically converted to numbers
const code = String.charCodeAt("Hello", "0");
print(code); // Outputs: 72 (the character code for 'H')

Handling out of range indices

// Accessing an index out of range
const invalidCode = String.charCodeAt("ABC", 10);
print(invalidCode); // Outputs: NaN

// Checking for valid character codes
function isValidChar(str: string, index: number) {
  const code = String.charCodeAt(str, index);
  return !isNaN(code);
}

print(isValidChar("Hello", 1)); // Outputs: true
print(isValidChar("Hello", 10)); // Outputs: false