SHA-1 a string in the browser

gistfile1.txt

function sha1(str) {
  function hex(buffer) {
    const hexCodes = [];
    const view = new DataView(buffer);
    for (let i = 0; i < view.byteLength; i += 4) {
      // Using getUint32 reduces the number of iterations needed (we process 4 bytes each time)
      const value = view.getUint32(i)
      // toString(16) will give the hex representation of the number without padding
      const stringValue = value.toString(16)
      // We use concatenation and slice for padding.
      hexCodes.push(`00000000${stringValue}`.slice(-8))
    }
    // Join all the hex strings into one
    return hexCodes.join('');
  }

  // We transform the string into an arraybuffer.
  const buffer = new TextEncoder('utf-8').encode(str);
  return crypto.subtle.digest('SHA-1', buffer).then(hash => hex(hash));
}