Convertir heures en hh:mm:ss dans un array

  var stringArray = new Array("1:3:12", "2:5:4", "3:1:1", "1:1:5");
  
  function formatHMS(arrDatas){
    var newArr = arrDatas.map(item => {
      let explodeItem = item.split(':');
      let newItem = explodeItem.map(elm=>{
        return parseInt(elm)<10 ? "0"+elm : elm;
      });
      return newItem.join(':');
    });
    return newArr;
  }
  
  formatHMS(stringArray);

let unix_timestamp = 1549312452
// Create a new JavaScript Date object based on the timestamp
// multiplied by 1000 so that the argument is in milliseconds, not seconds.
var date = new Date(unix_timestamp * 1000);
// Hours part from the timestamp
var hours = date.getHours();
// Minutes part from the timestamp
var minutes = "0" + date.getMinutes();
// Seconds part from the timestamp
var seconds = "0" + date.getSeconds();

// Will display time in 10:30:23 format
var formattedTime = hours + ':' + minutes.substr(-2) + ':' + seconds.substr(-2);
console.log(formattedTime);

var stringArray = new Array("1", "2", "3", "5");

for (var i = 0; i < stringArray.length ; i++) 
{
    var ix=parseInt(stringArray[i]);
    var test=[];
  	console.log(ix);
  	if(stringArray[i]<10){
    	console.log("0"+ix);
    }
  
}