SparkMD5
SparkMD5 is a fast md5 implementation of the MD5 algorithm.
This script is based in the JKM md5 library which is the fastest algorithm around. This is most suitable for browser usage, because nodejs version might be faster.
NOTE: Please disable Firebug while performing the test! Firebug consumes a lot of memory and CPU and slows the test by a great margin.
Install
npm install --save spark-md5
Improvements over the JKM md5 library
- Strings are converted to utf8, like most server side algorithms
- Fix computation for large amounts of data (overflow)
- Incremental md5 (see below)
- Support for array buffers (typed arrays)
- Functionality wrapped in a closure, to avoid global assignments
- Object oriented library
- CommonJS (it can be used in node) and AMD integration
- Code passed through JSHint and JSCS
Incremental md5 performs a lot better for hashing large amounts of data, such as files. One could read files in chunks, using the FileReader & Blob's, and append each chunk for md5 hashing while keeping memory usage low. See example below.
Usage
Normal usage
var hexHash = SparkMD5.hash('Hi there'); // hex hash
var rawHash = SparkMD5.hash('Hi there', true); // OR raw hash (binary string)
Incremental usage
var spark = new SparkMD5();
spark.append('Hi');
spark.append(' there');
var hexHash = spark.end(); // hex hash
var rawHash = spark.end(true); // OR raw hash (binary string)
Hash a file incrementally
NOTE: If you test the code bellow using the file:// protocol in chrome you must start the browser with -allow-file-access-from-files argument. Please see: http://code.google.com/p/chromium/issues/detail?id=60889
document.getElementById('file').addEventListener('change', function () {
var blobSlice = File.prototype.slice || File.prototype.mozSlice || File.prototype.webkitSlice,
file = this.files[0],
chunkSize = 2097152, // Read in chunks of 2MB
chunks = Math.ceil(file.size / chunkSize),
currentChunk = 0,
spark = new SparkMD5.ArrayBuffer(),
fileReader = new FileReader();
fileReader.onload = function (e) {
console.log('read chunk nr', currentChunk + 1, 'of', chunks);
spark.append(e.target.result); // Append array buffer
currentChunk++;
if (currentChunk < chunks) {
loadNext();
} else {
console.log('finished loading');
console.info('computed hash', spark.end()); // Compute hash
}
};
fileReader.onerror = function () {
console.warn('oops, something went wrong.');
};
function loadNext() {
var start = currentChunk * chunkSize,
end = ((start + chunkSize) >= file.size) ? file.size : start + chunkSize;
fileReader.readAsArrayBuffer(blobSlice.call(file, start, end));
}
loadNext();
});