JavaScript closures - { }

What is a closure

A closure is a [function] (a scope can access local variables of another function)

The role of closure

Extend the scope of variables

function f() {
    
    
    let num = 21;
    return function () {
    
    
        console.log(num);
    }
}
f()();
// 此时，函数f就是一个闭包（Closure）

Think about whether the example is a closure

window.name = 'window';
let obj = {
    
    
    name: 'obj',
    getName: function () {
    
    
        let that = this;
        return function () {
    
    
            return that.name;
        }
    }
}
console.log(obj.getName()());

window.name = 'window';
let obj = {
    
    
    name: 'obj',
    getName: function () {
    
    
        return function () {
    
    
            return this.name;
        }
    }
}
console.log(obj.getName()());