Bagaimanakah anda menyahkod rentetan UTF-8 base64 dalam JavaScript menggunakan `atob` sambil mengelakkan ralat pengekodan?

<code class="js">const notOK = "✓"
console.log(btoa(notOK)); // error</code>

<code class="js">const ok = "a";
console.log(ok.codePointAt(0).toString(16)); // 0x61: occupies 1 byte

const notOK = "✓";
console.log(notOK.codePointAt(0).toString(16)); // 0x2713: occupies 2 bytes</code>

<code class="js">function toBinary(string) {
  const codeUnits = new Uint16Array(string.length);
  for (let i = 0; i < codeUnits.length; i++) {
    codeUnits[i] = string.charCodeAt(i);
  }
  return btoa(String.fromCharCode(...new Uint8Array(codeUnits.buffer)));
}
encoded = toBinary("✓ à la mode") // "EycgAOAAIABsAGEAIABtAG8AZABlAA=="</code>

<code class="js">function fromBinary(encoded) {
  const binary = atob(encoded);
  const bytes = new Uint8Array(binary.length);
  for (let i = 0; i < bytes.length; i++) {
    bytes[i] = binary.charCodeAt(i);
  }
  return String.fromCharCode(...new Uint16Array(bytes.buffer));
}
decoded = fromBinary(encoded) // "✓ à la mode"</code>

<code class="js">function b64EncodeUnicode(str) {
    // Percent-encode Unicode, then convert to byte array
    return btoa(encodeURIComponent(str).replace(/%([0-9A-F]{2})/g,
        function(match, p1) {
            return String.fromCharCode('0x' + p1);
    }));
}
b64EncodeUnicode('✓ à la mode'); // "4pyTIMOgIGxhIG1vZGU="</code>

<code class="js">function b64DecodeUnicode(str) {
    // Convert byte array to percent-encoding, then decode
    return decodeURIComponent(atob(str).split('').map(function(c) {
        return '%' + ('00' + c.charCodeAt(0).toString(16)).slice(-2);
    }).join(''));
}
b64DecodeUnicode('4pyTIMOgIGxhIG1vZGU='); // "✓ à la mode"</code>

<code class="ts">function b64EncodeUnicode(str) {
    return btoa(encodeURIComponent(str).replace(/%([0-9A-F]{2})/g, function(match, p1) {
        return String.fromCharCode(parseInt(p1, 16))
    }))
}
function b64DecodeUnicode(str) {
    return decodeURIComponent(Array.prototype.map.call(atob(str), function(c) {
        return '%' + ('00' + c.charCodeAt(0).toString(16)).slice(-2)
    }).join(''))
}</code>