JSFiddle - React, Tailwind, and code Playground

JavaScript

newarr = [];
testarr = [];
duplicatearr = [];
locArray = [1,2,3,4,4,4,4,4,5,6,6,6];
for (var i = 0; i<locArray.length;i++)
{
var idx = $.inArray(locArray[i], testarr);
if (idx == -1) {
  testarr.push(locArray[i]);
  newarr.push(locArray[i]);
}
    else
    {  
        var id = $.inArray(locArray[i], duplicatearr);
        if (id == -1) {
        newarr.push(locArray[i]);
        duplicatearr.push(locArray[i]);
        }
        
    }
    
   
}
console.log(newarr);