Hashing strings in JS using the built-in SubtleCrypto library

hashPassword.js

const stringToUTF8Array = str => {
    const utf8 = [];
    for (let i = 0; i < str.length; i++) {
        let 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));
        } else {
            i++;
            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 new Uint8Array(utf8);
}

const binaryArrayToBase64 = async bin => {
    if (!bin || bin.length <= 0)
        return '';

    const blob = new Blob([bin], { type: 'application/octet-binary' });

    const reader = new FileReader();
    const promise = new Promise(resolve => {
        reader.onloadend = () => {
            resolve(reader.result ? reader.result.substr(reader.result.indexOf(',') + 1) : '');
        };
    });

    reader.readAsDataURL(blob);
    return await promise;
}

// Password
const password = "ThisIsSafe123";

// Get UTF8 bytes from the string password
const utfBytesPassword = stringToUTF8Array(password);

// Generate SHA-512 hash
const sha512Hash = await crypto.subtle.digest('SHA-512', utfBytesPassword);

// Base64 SHA512 string
const encodedPasswordHash = await binaryArrayToBase64(sha512Hash);

console.log(encodedPasswordHash);