编辑代码



const arr = [1,2,3,4,5];

function myItertor(arr) {
    let index = 0;
    return {
        next: function() {
            const value = arr[index]
            let obj;
            if(value) {
                obj = {
                    value: arr[index],
                    done: false
                }
                index++
            } else {
                obj = {
                    value: undefined,
                    done: true
                }
            }
            return obj
        }
    }
}

const a = myItertor(arr);
console.log(a.next());
console.log(a.next());
console.log(a.next());
console.log(a.next());
console.log(a.next());
console.log(a.next());

const b = arr[Symbol.iterator]()
console.log(b.next())
console.log(b.next())
console.log(b.next())
console.log(b.next())
console.log(b.next())
console.log(b.next())