Default Arguments in ES2015

default-args-1.js

function calculateBill(total, tax = 0.15, tip = 0.05){
  console.log(total + (total * tax) + (total * tip));
}
              
              
// usage
calculateBill(500); // 600
  
calculateBill(500, 0.2); // 625

calculateBill(500, 0.2, 0.3); // 750
  
calculateBill(500, undefined, 0.3); // 725
  
            

default-args-2.js

function calculateBill(total, {tax = 0.15, tip = 0.05}){
  console.log(total + (total * tax) + (total * tip));
}
              
              
// usage
calculateBill(500, {}); // 600
  
calculateBill(500, {tax: 0.2}); // 625

calculateBill(500, {tip: 0.3}); // 750
  
calculateBill(500, {tax: 0.2, tip: 0.3}); // 725

default-args-3.js

function calculateBill(total, {tax = 0.15, tip = 0.05} = {}){
  console.log(total + (total * tax) + (total * tip));
}
              
              
// usage
calculateBill(500); // 600