// IIFE Goal: Create a new scope, return the data just once. All of data inside IIFE will be private as it would inside the fn scope.
// Using this way, we don't need to call it separately. And it ensures its called only once.
// IIFE is created only once, goal is 'NOT TO REUSE' by executing it multiple times.
// Result of running an IIFE is stored, or else it will disappear simply.
const ShoppingCart2 = (function(){
const cart = [];
const shippingCost = 10;
const totalPrice = 237;
const totalQuantity = 10;
const addToCart = function(product, quantity){
cart.push({product, quantity});
console.log(`${quantity} ${product} added to cart. Shipping cost is ${shippingCost}`);
};
const orderStock = function(product, quantity){
console.log(`${quantity} ${product} ordered from supplier`);
};
// Need to return something, in order to return a public API. For that, an object is returned containing stuff which needs to be made public.
return {
addToCart,
cart,
totalPrice,
totalQuantity
};
})();
// Everything inside the above module is private to the module.
// The above fn returns the object mentioned inside return statement and assign it to the ShoppingCart2 variable mentioned at the start of fn. This IIFE is returned then long ago.
// All this is possible because of closures. Hence, addToCart can acccess the cart variable.
ShoppingCart2.addToCart('apple', 4);
ShoppingCart2.addToCart('pizza', 5);
ShoppingCart2;
ShoppingCart2.shippingCost; // inaccessible.
缺点：
除了原生的 ES6 模块和模块模式之外，JS 还支持其他非 JS 原生的模块系统。前任。 AMD、CommonJS
前任。 Node.js 中自始至终都使用 CommonJS 模块。最近 ES6 模块已经在 Node.js 中实现
npm 存储库上的所有模块仍然使用 commonJS 模块系统，因为 npm 最初是为 Node 设计的。直到后来，npm 才成为整个 JS 世界的存储库。因此，我们基本上只能使用 CommonJS。所以，CommonJS 在 Node.js 中的作用还是需要关注的
就像 ES6 模块一样，CommonJS 中 1 个文件就是 1 个模块。
commonJS 代码在浏览器中不起作用，但在 Node.js 中可以
ES Modules 最终将取代所有模块系统，但目前我们还需要使用 commonjs。
export 关键字是一个对象，它没有在我们的代码中以及浏览器中定义。
// EXPORT
export.addToCart = function(product, quantity){
cart.push({product, quantity});
console.log(`${quantity} ${product} added to cart. Shipping cost is ${shippingCost}`);
};
// IMPORT: is similar to ES Modules but would use a require fn.
// require is not defined in browser env but its defined in node env as its a part of commonjs
const addToCart = require('./shoppingCart.js')
以上是模块的详细内容。更多信息请关注PHP中文网其他相关文章！
