SOURCE

console.log(typeof undefind)
console.log(typeof null)

const c = 1;

console.log(c.constructor)

const b = {}
console.log(b instanceof Object)


var arr = [344, 45, 34, 23]; //一个普通数组

console.log(Object.toString())
console.log(Object.prototype.toString())

console.log(arr.__proto__ === Array.prototype);                 // true
console.log(arr.__proto__.__proto__ === Object.prototype);      // true
console.log(Array.prototype.hasOwnProperty('push'));            // true
console.log(Array.prototype.hasOwnProperty('splice'));          // true


//Json对象转数组
const obj = {'未完成':5, '已完成':8, '待确认':4, '已取消':6}
const arrs = [];
for(let i in obj){
    let item = {};
    item[i] = obj[i]
    arrs.push(item)
}
console.log(arrs)