JSFiddle - React, Tailwind, and code Playground

JavaScript

var array1 = [1,5,50,4,12,3,60];
      
      var array2 = [12,1,5,4,43,3,60];
      
      
      alert(mySpecialMerge(array1,array2));
      
      function mySpecialMerge(array1,array2) {
          var pos;
          var array3=[];
          for(var i=0;i<array1.length;i++) {
              pos=array2.indexOf(array1[i]);
            if(pos!=-1) {
              array3.push(array1[i]);
              array2.splice(pos,1);
            }
          }
          return array2.concat(array3);
      }