JavaScript: String.prototype.charCodeAt

str.charCodeAt(index)

Return a integer that's the String Code Unit at index index in str.

console.log("abc".charCodeAt(0) === 97);

If the string contains NON-ASCII character, result may not be what you expect.

console.log("😂".charCodeAt(0) === 55357);
console.log("😂".charCodeAt(0) === 0xd83d);

/* [
😂
name: FACE WITH TEARS OF JOY
codepoint decimal: 128514
codepoint hexadecimal: 1f602
UTF-8 encoding: F0 9F 98 82
UTF-16 encoding: D8 3D DE 02

since the char 😂 in UTF-16 encoding is D8 3D DE 02,
so the first byte in hexadecimal is D83D,
which in decimal is 55357.
therefore its charCode at 0th index is 55357.
] */