JSFiddle - React, Tailwind, and code Playground

JavaScript

var dob = function (array) {
    var test = [];
   for(var i = 0; i<array.length; i++) {
       var sum = array[i];
       test.push(sum);test.push(sum);
  }
   console.log(test);
  };

dob([1,2,3])