Deferred Implmentation of spark md5 js library.

spark MD5 usage.js

function getFileMd5 ( file ) {
	var dfd = jQuery.Deferred();
	/**
	 * reference:
	 * 	https://github.com/satazor/SparkMD5
	 */
    var blobSlice = File.prototype.slice || File.prototype.mozSlice || File.prototype.webkitSlice,
        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) {
        dfd.notify('read chunk # ' + (currentChunk + 1) + ' of ' + chunks);
        spark.append(e.target.result);                   // Append array buffer
        currentChunk++;

        if (currentChunk < chunks) {
            loadNext();
        } else {
            dfd.resolve( spark.end() );
        }
    };

    fileReader.onerror = function () {
        dfd.reject('oops, something went wrong.');
    };

    var loadNext = function() {
        var start = currentChunk * chunkSize,
            end = ((start + chunkSize) >= file.size) ? file.size : start + chunkSize;

        fileReader.readAsArrayBuffer(blobSlice.call(file, start, end));
    };

    loadNext();

    return dfd.promise();
}

@meyer59, sorry for the late reply.

first, you should include the dependencies/libraries. SparkMD5 and jQuery

the getFileMd5 method's file parameter accepts FIle class.
https://developer.mozilla.org/en-US/docs/Web/API/File

File objects are generally retrieved from a FileList object returned as a result of a user selecting files using the element...

I used this with DropzoneJs. This is my implementation.

    dropzone_uploader.on('addedfile', function ( file ) {
        getFileMd5( file ).done( function ( result, file ) {
            //your code here
        });
    });