Properly handle files with 0 filesize

Fixes #1079

src/dropzone.coffee

@@ -814,18 +814,21 @@ class Dropzone extends Emitter
 
   # Returns a nicely formatted filesize
   filesize: (size) ->
-    units = [ 'TB', 'GB', 'MB', 'KB', 'b' ]
-    selectedSize = selectedUnit = null
+    selectedSize = 0
+    selectedUnit = "b"
 
-    for unit, i in units
-      cutoff = Math.pow(@options.filesizeBase, 4 - i) / 10
+    if size > 0
+      units = [ 'TB', 'GB', 'MB', 'KB', 'b' ]
 
-      if size >= cutoff
-        selectedSize = size / Math.pow(@options.filesizeBase, 4 - i)
-        selectedUnit = unit
-        break
+      for unit, i in units
+        cutoff = Math.pow(@options.filesizeBase, 4 - i) / 10
+
+        if size >= cutoff
+          selectedSize = size / Math.pow(@options.filesizeBase, 4 - i)
+          selectedUnit = unit
+          break
 
-    selectedSize = Math.round(10 * selectedSize) / 10 # Cutting of digits
+      selectedSize = Math.round(10 * selectedSize) / 10 # Cutting of digits
 
     "<strong>#{selectedSize}</strong> #{selectedUnit}"
 

test/test.coffee

@@ -871,6 +871,9 @@ describe "Dropzone", ->
 
     describe ".filesize()", ->
 
+      it "should handle files with 0 size properly", ->
+        dropzone.filesize(0).should.eql "<strong>0</strong> b"
+
       it "should convert to KiloBytes, etc..", ->
 
         dropzone.options.filesizeBase.should.eql 1000 # Just making sure the default config is correct