JS: String.prototype.charAt

str.charAt(index)

Return a string of length 1 that's the code unit (character) at index index of str.

example:

"abc".charAt(0) === "a"

Return empty string if index is out of bound.

console.log ( "abc".charAt(1) === "b" ); // true

Note, when the string contains NON-ASCII character, result may not be expected.

[see JS: Character, Code Unit, Codepoint]

console.log ( "😂".charAt(0) !== "😂" ); // true

console.log ( "😂".charAt(0) === String.fromCharCode ( 0xd83d ) ); // true

// 😂
// name: FACE WITH TEARS OF JOY
// codepoint decimal: 128514
// codepoint hexadecimal: 1f602
// UTF8 encoding: F0 9F 98 82
// Utf16 encoding: D8 3D DE 02

If index is out of bound, return empty string.

console.log ( "abc".charAt(9) === "" ); // true