//It's merge arr1 and arr2 , delete the same element only leave one
//It's only apdapter array. If object, no. 
//The sequence of the two array is not required.
mergeArray:function (arr1, arr2){ 
 for (var i = 0 ; i < arr1.length ; i ++ ){
   for(var j = 0 ; j < arr2.length ; j ++ ){
    if (arr1[i] === arr2[j]){
     arr1.splice(i,1); //利用splice函数删除元素，从第i个位置，截取长度为1的元素
    }
   }
 }
 //alert(arr1.length)
 for(var i = 0; i <arr2.length; i++){
  arr1.push(arr2[i]);
 }
 return arr1;
}