Building Applications with Spring 5 and Vue.js 2

Default parameter value

In ES6, you can define the default values of a function's parameters. This is quite a useful improvement because the equivalent implementation in ES5 is not only tedious but also decreases the readability of the code.

Let's see an example here:

const shoppingCart = [];function addToCart(item, size = 1) {  shoppingCart.push({item: item, count: size});}addToCart('Apple');     // size is 1addToCart('Orange', 2); // size is 2

In this example, we give the parameter size a default value, 1. And let's see how we can archive the same thing in ES5. Here is an equivalent of the addToCart function in ES5:

function addToCart(item, size) {  size = (typeof size !== 'undefined') ? size : 1;  shoppingCart.push({item: item, count: size}); ...