SOURCE

const person = {
    name: '胡杰',
    age: 18,
    [Symbol('admirer')]: '小花'
}

// Object.prototype[Symbol.iterator] = function () {
//     let _this = this
//     const keys = Reflect.ownKeys(_this)
//     let index = 0
//     return {
//         next() {
//             if(index<keys.length) {
//                 return {value: _this[keys[index++]],done: false}
//             } else {
//                 return {value: undefined, done: true}
//             }
//         }
//     }
// }

Object.prototype[Symbol.iterator] = function () {
    let that = this
    const keys = Reflect.ownKeys(that)
    const length = keys.length
    let index = 0
    return {
        next() {
            if (index <= length - 1) {
                return {
                    value: that[keys[index++]],
                    done: false
                }
            } else {
                return {
                    value: undefined,
                    done: true
                }
            }
        }
    }




}

console.log('---------for in----------')
for (key in person) {
    console.log(person[key])
}
console.log('---------for of----------')
for (value of person) {
    console.log(value)
}