amakukha/djb2_32.html

## djb2_32.html
<html>
<body>
<h2>32-bit DJB2 hash in JavaScript demo</h2>
<input type="file" id="file-input" />
<h3 id="result">Select file to calculate DJB2 hash</h3>
</body>
<script>

// DJB2 hash function. Takes ArrayBuffer
function hash_buf_djb2_32(buf) {
  var hash = 5381;
  let view = new Uint8Array(buf);
  for (let num of view)
    hash = ((hash << 5) + hash + num) & 0xFFFFFFFF;
  return hash >>> 0;
}

function readSingleFile(e) {
  var file = e.target.files[0];
  if (!file) {
    return;
  }
  var reader = new FileReader();
  reader.onload = function(e) {
    var contents = e.target.result;
    displayContents(contents);
  };
  reader.readAsArrayBuffer(file);
}

function displayContents(contents) {
  var element = document.getElementById('result');
  element.textContent = "Hash = " + hash_buf_djb2_32(contents) + ", Len = " + contents.byteLength;
}

document.getElementById('file-input')
  .addEventListener('change', readSingleFile, false);
</script>
</html>

## djb2_32.js
// 32-bit DJB2 hash in JavaScript
// DJB2 is probably the simplest among relatively good checksum and hash functions.
// DJB2 outperforms CRC32 in speed and comes close to it in performance.
// You should still use CRC32, especially if your CPU supports CRC calculation natively.
// On 32-bit or 64-bit architectures, MurmurHash can outperform DJB2.

// Takes ArrayBuffer
function hash_buf_djb2_32(buf) {
  var hash = 5381;
  let view = new Uint8Array(buf);
  for (let num of view)
    hash = ((hash << 5) + hash + num) & 0xFFFFFFFF;
  return hash >>> 0;
}

// Takes string (NOTE: charCode can be larger than 255)
function hash_str_djb2_32(str) {
  var len = str.length;
  var hash = 5381;
  for (var idx = 0; idx < len; ++idx) {
    hash = ((hash << 5) + hash + str.charCodeAt(idx)) & 0xFFFFFFFF;
  }
  return hash >>> 0;
}
	<html>
	<body>
	<h2>32-bit DJB2 hash in JavaScript demo</h2>
	<input type="file" id="file-input" />
	<h3 id="result">Select file to calculate DJB2 hash</h3>
	</body>
	<script>

	// DJB2 hash function. Takes ArrayBuffer
	function hash_buf_djb2_32(buf) {
	var hash = 5381;
	let view = new Uint8Array(buf);
	for (let num of view)
	hash = ((hash << 5) + hash + num) & 0xFFFFFFFF;
	return hash >>> 0;
	}

	function readSingleFile(e) {
	var file = e.target.files[0];
	if (!file) {
	return;
	}
	var reader = new FileReader();
	reader.onload = function(e) {
	var contents = e.target.result;
	displayContents(contents);
	};
	reader.readAsArrayBuffer(file);
	}

	function displayContents(contents) {
	var element = document.getElementById('result');
	element.textContent = "Hash = " + hash_buf_djb2_32(contents) + ", Len = " + contents.byteLength;
	}

	document.getElementById('file-input')
	.addEventListener('change', readSingleFile, false);
	</script>
	</html>
	// 32-bit DJB2 hash in JavaScript
	// DJB2 is probably the simplest among relatively good checksum and hash functions.
	// DJB2 outperforms CRC32 in speed and comes close to it in performance.
	// You should still use CRC32, especially if your CPU supports CRC calculation natively.
	// On 32-bit or 64-bit architectures, MurmurHash can outperform DJB2.

	// Takes ArrayBuffer
	function hash_buf_djb2_32(buf) {
	var hash = 5381;
	let view = new Uint8Array(buf);
	for (let num of view)
	hash = ((hash << 5) + hash + num) & 0xFFFFFFFF;
	return hash >>> 0;
	}

	// Takes string (NOTE: charCode can be larger than 255)
	function hash_str_djb2_32(str) {
	var len = str.length;
	var hash = 5381;
	for (var idx = 0; idx < len; ++idx) {
	hash = ((hash << 5) + hash + str.charCodeAt(idx)) & 0xFFFFFFFF;
	}
	return hash >>> 0;
	}