playwithString.js

var inputString = "dilip %s Kumar %s";
var finalString;
function manipulateString(param) {
  finalString = inputString;
  for(var i = 0; i <= arguments.length; i++) {
     finalString = finalString.replace('%s',arguments[i]);
  }
  return finalString;
}
console.log(manipulateString("is", "cool"));