在浏览器中获取文件或字串的md5的js源代码

# SparkMD5 SparkMD5 is a fast md5 implementation of the MD5 algorithm. This script is based in the JKM md5 library which is the [fastest](http://jsperf.com/md5-shootout/7) 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. **[Demo](http://9px.ir/demo/incremental-md5.html)** ## 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 bellow) * 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 bellow. ## Usage ### Normal usage ```js var hexHash = SparkMD5.hash('Hi there'); // hex hash var rawHash = SparkMD5.hash('Hi there', true); // OR raw hash (binary string) ``` ### Incremental usage ```js 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 ```js 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(); }); ``` You can see some more examples in the test folder. ## Documentation ### SparkMD5 class #### SparkMD5#append(str) Appends a string, encoding it to UTF8 if necessary. #### SparkMD5#appendBinary(str) Appends a binary string (e.g.: string returned from the deprecated [readAsBinaryString](https://developer.mozilla.org/en-US/docs/Web/API/FileReader/readAsBinaryString)). #### SparkMD5#end(raw) Finishes the computation of the md5, returning the hex result. If `raw` is true, the result as a binary string will be returned instead. #### SparkMD5#reset() Resets the internal state of the computation. #### SparkMD5#getState() Returns an object representing the internal computation state. You can pass this state to setState(). This feature is useful to resume an incremental md5. #### SparkMD5#setState(state) Sets the internal computation state. See: getState(). #### SparkMD5#destroy() Releases memory used by the incremental buffer and other additional resources. #### SparkMD5.hash(str, raw) Hashes a string directly, returning the hex result. If `raw` is true, the result as a binary string will be returned instead. Note that this function is `static`. #### SparkMD5.hashBinary(str, raw) Hashes a binary string directly (e.g.: string returned from the deprecated [readAsBinaryString](https://developer.mozilla.org/en-US/docs/Web/API/FileReader/readAsBinaryString)), returning the hex result. If `raw` is true, the result as a binary string will be returned instead. Note that this function is `static`. ### SparkMD5.ArrayBuffer class #### SparkMD5.ArrayBuffer#append(arr) Appends an array buffer. #### SparkMD5.ArrayBuffer#end(raw) Finishes the computation of the md5, returning the hex result. If `raw` is true, the result as a binary string will be returned instead. #### SparkMD5.ArrayBuffer#reset() Resets the internal state of the computation. #### SparkMD5.ArrayBuffer#destroy() Releases memory used by the incremental buffer and other additional resources. #### SparkMD5.ArrayBuffer#getState() Returns an object representing the internal computation state. You can pass this state to setState(). This feature is useful to resume an incremental md5. #### SparkMD5.ArrayBuffer#setState(state) Sets the internal computation state. See: getState(). #### SparkMD5.ArrayBuffer.hash(arr, raw) Hashes an array buffer directly, returning the hex result. If `raw` is true, the result as a binary string will be returned instead. Note that this function is `static`. ## Credits [Joseph Myers](http://www.myersdaily.org/joseph/javascript/md5-text.html)