hex.js

// https://github.com/danfinlay/browser-string-hexer/blob/main/index.js
export default function hexer(input) {
    const utf8 = toUTF8Array(input)
    const hex = utf8.map((n) => n.toString(16))
    return '0x' + hex.join('')
}

// From https://stackoverflow.com/a/18729931
function toUTF8Array(str) {
    var utf8 = []
    for (var i = 0; i < str.length; i++) {
        var charcode = str.charCodeAt(i)
        if (charcode < 0x80) utf8.push(charcode)
        else if (charcode < 0x800) {
            utf8.push(0xc0 | (charcode >> 6), 0x80 | (charcode & 0x3f))
        } else if (charcode < 0xd800 || charcode >= 0xe000) {
            utf8.push(0xe0 | (charcode >> 12), 0x80 | ((charcode >> 6) & 0x3f), 0x80 | (charcode & 0x3f))
        }
        // surrogate pair
        else {
            i++
            // UTF-16 encodes 0x10000-0x10FFFF by
            // subtracting 0x10000 and splitting the
            // 20 bits of 0x0-0xFFFFF into two halves
            charcode = 0x10000 + (((charcode & 0x3ff) << 10) | (str.charCodeAt(i) & 0x3ff))
            utf8.push(
                0xf0 | (charcode >> 18),
                0x80 | ((charcode >> 12) & 0x3f),
                0x80 | ((charcode >> 6) & 0x3f),
                0x80 | (charcode & 0x3f)
            )
        }
    }
    return utf8
}