Implement isSubsetOf.js

isSubsetOf/isSubsetOf.js

@@ -12,6 +12,20 @@
  * including non-strings.
 */
 
-Array.prototype.isSubsetOf = function(array){
-  // Your code here
-};
+Array.prototype.isSubsetOf = function (array) {
+  var subset    = this;
+  var subsetLen = subset.length;
+  var supersetLen = array.length;
+  var first, found;
+
+  // base case
+  if ( subsetLen > supersetLen ) return false;
+  if ( subsetLen === 0 && supersetLen >= 0 ) return true;
+
+  // supLen is greater than or equal to subLen and supLen is greater than 0
+  first = subset[0];
+  found = array.indexOf( first );
+
+  if ( found === -1 ) return false;
+  return subset.slice(1).isSubsetOf( Array.prototype.concat( array.slice(0, found), array.slice(found + 1) ) );
+};