Convert Hex to String in JavaScript (Browser and Node)

JavaScript hex → string conversion is: parse hex pairs into bytes, then decode those bytes as text (UTF-8 in modern apps). Browser and Node APIs differ slightly; the mental model does not.

Test payloads quickly with Hex to String. Background: What is hexadecimal encoding?.

Node.js: Buffer (simplest)

const hex = "48656c6c6f";
const text = Buffer.from(hex, "hex").toString("utf8");
console.log(text); // Hello

// string → hex
console.log(Buffer.from("Hello", "utf8").toString("hex"));

Odd-length hex throws in modern Node. Prefer failing loudly over padding.

Browser: TypedArray + TextDecoder

function hexToBytes(hex) {
  const clean = hex.replace(/\s+/g, "").replace(/^0x/i, "");
  if (clean.length % 2) throw new Error("hex length must be even");
  if (!/^[0-9a-fA-F]*$/.test(clean)) throw new Error("invalid hex");
  const out = new Uint8Array(clean.length / 2);
  for (let i = 0; i < clean.length; i += 2) {
    out[i / 2] = parseInt(clean.slice(i, i + 2), 16);
  }
  return out;
}

function hexToString(hex, encoding = "utf-8") {
  return new TextDecoder(encoding).decode(hexToBytes(hex));
}

console.log(hexToString("e4bda0e5a5bd")); // 你好

ASCII-only shortcut (limited)

function hexToAscii(hex) {
  const clean = hex.replace(/\s+/g, "");
  let s = "";
  for (let i = 0; i < clean.length; i += 2) {
    s += String.fromCharCode(parseInt(clean.slice(i, i + 2), 16));
  }
  return s;
}

Fine for protocol bytes in the 0–127 range. Do not use it for UTF-8 multi-byte text — use TextDecoder or Buffer instead.

Pitfalls

• Color codes are not “names”: #FF5733 converts to RGB channels, not the word “coral”. Use Hex to RGB for colors.
• Odd length: reject or follow an explicit format rule — do not silently prepend 0.
• Encoding: bytes from a Windows-1252 source will look wrong if you decode as UTF-8.

Round-trip check

const original = "café";
const hex = Buffer.from(original, "utf8").toString("hex");
const back = Buffer.from(hex, "hex").toString("utf8");
console.assert(original === back);

Related: String to Hex tool · Python guide · PHP guide.