--- /dev/null
+module.exports = ByteCounter;
+
+var Writable = require('readable-stream').Writable;
+var util = require('util');
+
+util.inherits(ByteCounter, Writable);
+function ByteCounter(options) {
+ Writable.call(this, options);
+ this.bytes = 0;
+}
+
+ByteCounter.prototype._write = function(chunk, encoding, cb) {
+ this.bytes += chunk.length;
+ this.emit('progress');
+ cb();
+};