Difference of charCodeAt and codePointAt: How can we get "code point" from Unicode surrogate pair?

The JS function “charCodeAt(0)” doesn’t seem to return the correct Unicode code point in case of emoji.

const letter = '😀'

const code0 = letter.charCodeAt(0).toString(16)
const code1 = letter.charCodeAt(1).toString(16)

console.log(code0, code1)
// d83d de00

Many symbols recently added to Unicode have two code points, which is called “surrogate pair”.

😀 = d83d + de00

In UTF-16, the surrogate pair can be expressed one code point.

😀 = d83d + de00
😀 = 1f600

const letter = '😀'

const codePoint = letter.codePointAt(0).toString(16)

console.log(codePoint)
// 1f600