The front-end uses spark-md5.js to calculate the MD5 of local files

Background:

Use:

            var running = false; //running Indicates whether MD5 is being calculatedfunction doNormalTest(input) {// It is assumed that a DOM reference to the file selection box is passed in directlyif(running) {// If the next calculation is being performed, the next calculation is not allowed to startreturn;
                }
 
                var fileReader = new FileReader(),    //创建FileReader实例
                    time;
 
                fileReader.onload = function(e) {//FileReader load event, running = triggered when the file is finished readingfalse; // e.target points to the fileReader instance aboveif(file.size ! = e.target.result.length) {// If the two are inconsistent, the reading error alert("ERROR:Browser reported success but could not read the file until the end.");
                    } else{ console.log(Finished loading! success!!) ;returnSparkMD5.hashBinary(e.target.result); // calculate md5 and return result}}; fileReader.onerror =function() {// If there is an error in reading the file, cancel reading state and popup box error running =false;
                    alert("ERROR:FileReader onerror was triggered, maybe the browser aborted due to high memory usage.");
                };
 
                running = true; fileReader.readAsBinaryString( input.files[0] ); // Use fileReader to read file binary};Copy the code

Here is the second method:

            function doIncrementalTest(INPUT) {// This assumes that the DOM reference to the file selection box is passed directlyif (running) {
                    return; } // We need the File slice() method, Here are compatible writing var blobSlice = File. The prototype. Slice | | File. The prototype. MozSlice | | File. The prototype. WebkitSlice, File = input.files[0], chunkSize = 2097152, // chunks = math.ceil (file.size/chunkSize), CurrentChunk = 0, spark = new SparkMD5(), // Create SparkMD5 instance time, fileReader = new fileReader (); fileReader.onload =function (e) {
 
                    console("Read chunk number (currentChunk + 1) of chunks ");
 
                    spark.appendBinary(e.target.result);                 // append array buffer
                    currentChunk += 1;
 
                    if (currentChunk < chunks) {
                        loadNext();
                    } else {
                        running = false;
                        console.log("Finished loading!");
                        returnspark.end(); // Complete the calculation, return the result}}; fileReader.onerror =function () {
                    running = false;
                    console.log("something went wrong");
                };
 
                function loadNext() {
                    var start = currentChunk * chunkSize,
                        end = start + chunkSize >= file.size ? file.size : start + chunkSize;
 
                    fileReader.readAsBinaryString(blobSlice.call(file, start, end));
                }
 
                running = true;
                loadNext();
            } 
Copy the code

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