es6_default_parameter.js

//Without Default Parameters
function sell(seller, price){
  price = price || 2;
  seller = seller || "John";
  
  console.log(seller + " is selling at $"+price); 
}

//With Default Parameters
function sellWithDefault(seller = "John", price = 2){
  console.log(seller + " is selling at $"+price);
}

sell(); // John is selling at $2
sellWithDefault(); // John is selling at $2