Fixed lastIndexOf. Added test of implementation

Author: plusdude

array.generics.js

@@ -153,7 +153,7 @@
  begin = toInteger(begin);
 
  // handle -begin, begin > length - 1
- index = 0 > begin ? Math.max(length + begin, 0) : Math.min(begin, length - 1);
+ index = 0 > begin ? length - Math.abs(begin) : Math.min(begin, length - 1);
  } else {
  // default value
  index = length - 1;
@@ -456,17 +456,53 @@
  }
  }
 
+ /**
+ * Helper function.
+ * Tests implementation of standard Array method.
+ */
+ function supportsStandard(key) {
+ var support = true;
+ if (Array.prototype[key]) {
+ try {
+ Array.prototype[key].call(undefined, /test/, null);
+ support = false;
+ } catch (e) {}
+ } else {
+ support = false;
+ }
+ return support;
+ }
+
+ /**
+ * Helper function.
+ * Tests implementation of generic Array method.
+ */
+ function supportsGeneric(key) {
+ var support = true;
+ if (Array[key]) {
+ try {
+ Array[key](undefined, /test/, null);
+ support = false;
+ } catch (e) {}
+ } else {
+ support = false;
+ }
+ return support;
+ }
+
  /**
  * Helper function.
  * Assigns method to Array constructor.
  */
  function extendArray(key) {
- Array[key] = Array[key] || makeStatic(key);
+ if (!supportsGeneric(key)) {
+ Array[key] = makeStatic(key);
+ }
  }
 
  /**
  * Helper function.
- * Creates static method from an instance method.
+ * Creates generic method from an instance method.
  */
  function makeStatic(key) {
  return function (value) {
@@ -495,10 +531,14 @@
  "reduce": reduce,
  "reduceRight": reduceRight
  };
+
  for (var key in ES5) {
  if (ES5.hasOwnProperty(key)) {
+
+ if (!supportsStandard(key)) {
+ Array.prototype[key] = ES5[key];
+ }
  extendArray(key);
- Array.prototype[key] = Array.prototype[key] || ES5[key];
  }
  }
  Array.isArray = Array.isArray || isArray;