fix #153 (#159)

karax/vdom.nim

@@ -303,6 +303,12 @@ proc sameAttrs*(a, b: VNode): bool =
 proc addEventListener*(n: VNode; event: EventKind; handler: EventHandler) =
   n.events.add((event, handler, nil))
 
+when kstring is cstring:
+  proc len(a: kstring): int =
+    # xxx: maybe move where kstring is defined
+    # without this, `n.field.len` fails on js (non web) platform
+    if a == nil: 0 else: a.len
+
 template toStringAttr(field) =
   if n.field.len > 0:
     result.add " " & astToStr(field) & " = " & $n.field

karax/vstyles.nim

@@ -235,6 +235,9 @@ proc eq*(a, b: VStyle): bool =
   return true
 
 proc setAttr*(s: VStyle; a, value: kstring) {.noSideEffect.} =
+  ## inserts (a, value) in sorted order of key `a`
+  # worst case quadratic complexity (if given styles in reverse order), hopefully
+  # not a concern assuming small cardinal
   var i = 0
   while i < s.len:
     if s[i] == a:
@@ -243,8 +246,8 @@ proc setAttr*(s: VStyle; a, value: kstring) {.noSideEffect.} =
     elif s[i] > a:
       s.add ""
       s.add ""
-      # insertion point here:
-      for j in countdown(s.len-1, i, 2):
+      # insertion point here, shift all remaining pairs by 2 indexes
+      for j in countdown(s.len-1, i+3, 2):
         s[j] = s[j-2]
         s[j-1] = s[j-3]
       s[i] = a