chunking.js

function parseFile(file, oboeInstance) {
    var fileSize = file.size;
    var chunkSize = 512 * 1024; // 512 kb
    var offset = 0;
    var self = this; // we need a reference to the current object
    var chunkReaderBlock = null;
    var readEventHandler = function(evt) {
        if (evt.target.error == null) {
            offset += evt.target.result.length;
            var chunk = evt.target.result;
            oboeInstance.emit('data', chunk); // callback for handling read chunk
        } else {
            console.log("Read error: " + evt.target.error);
            return;
        }
        if (offset >= fileSize) {
            os.emit('done');
            console.log("Done reading file");
        }

        // of to the next chunk
        chunkReaderBlock(offset, chunkSize, file);
    }

    chunkReaderBlock = function(_offset, length, _file) {
        var r = new FileReader();
        var blob = _file.slice(_offset, length + _offset);
        r.onload = readEventHandler;
        r.readAsText(blob);
    }

    // now let's start the read with the first block
    chunkReaderBlock(offset, chunkSize, file);
}