perf(jqLite): cache collection length for all methods that work on a …

…single element

This affects jqLite#html, #text, #attr, #prop, #css and others.

src/jqLite.js

@@ -636,6 +636,7 @@ forEach({
    */
   JQLite.prototype[name] = function(arg1, arg2) {
     var i, key;
+    var nodeCount = this.length;
 
     // jqLiteHasClass has only two arguments, but is a getter-only fn, so we need to special-case it
     // in a way that survives minification.
@@ -645,7 +646,7 @@ forEach({
       if (isObject(arg1)) {
 
         // we are a write, but the object properties are the key/values
-        for (i = 0; i < this.length; i++) {
+        for (i = 0; i < nodeCount; i++) {
           if (fn === jqLiteData) {
             // data() takes the whole object in jQuery
             fn(this[i], arg1);
@@ -659,9 +660,10 @@ forEach({
         return this;
       } else {
         // we are a read, so read the first child.
+        // TODO: do we still need this?
         var value = fn.$dv;
         // Only if we have $dv do we iterate over all, otherwise it is just the first element.
-        var jj = (value === undefined) ? Math.min(this.length, 1) : this.length;
+        var jj = (value === undefined) ? Math.min(nodeCount, 1) : nodeCount;
         for (var j = 0; j < jj; j++) {
           var nodeValue = fn(this[j], arg1, arg2);
           value = value ? value + nodeValue : nodeValue;
@@ -670,7 +672,7 @@ forEach({
       }
     } else {
       // we are a write, so apply to all children
-      for (i = 0; i < this.length; i++) {
+      for (i = 0; i < nodeCount; i++) {
         fn(this[i], arg1, arg2);
       }
       // return self for chaining