javascript read binary file

1function fileFilter(file, fnLineFilter, fnComplete) {
2     var bPos = 0,
3         mx = file.size,
4         BUFF_SIZE = 262144,
5         i = 0,
6         collection = [],
7         lineCount = 0;
8     var d1 = +new Date;
9     var remainder = "";
10
11     function grabNextChunk() {
12
13         var myBlob = file.slice(BUFF_SIZE * i, (BUFF_SIZE * i) + BUFF_SIZE, file.type);
14         i++;
15
16         var fr = new FileReader();
17
18         fr.onload = function(e) {
19
20             //run line filter:
21             var str = remainder + e.target.result,
22                 o = str,
23                 r = str.split(/\r?\n/);
24             remainder = r.slice(-1)[0];
25             r.pop();
26             lineCount += r.length;
27
28             var rez = r.map(fnLineFilter).filter(Boolean);
29             if (rez.length) {
30                 [].push.apply(collection, rez);
31             } /* end if */
32
33             if ((BUFF_SIZE * i) > mx) {
34                 fnComplete(collection);
35                 console.log("filtered " + file.name + " in " + (+new Date() - d1) + "ms  ");
36             } /* end if((BUFF_SIZE * i) > mx) */
37             else {
38                 setTimeout(grabNextChunk, 0);
39             }
40
41         };
42         fr.readAsText(myBlob, myBlob.type);
43     } /* end grabNextChunk() */
44
45     grabNextChunk();
46 } /* end fileFilter() */