js把一个包含多个属性的对象，拷贝部分属性到一个新的对象

let arr = [{name: "lucy", age: 100, sex: "female"}, {name: "mary", age: 43, sex: "female"}, {name: "curry", age: 30, sex: "male"}, {name: "bob", age: 20, sex: "male"}]

let targetArr = [{name: "lucy", age: 100}, {name: "mary", age: 43}, {name: "curry", age: 30}, {name: "bob", age: 20}]

arr数组中的每个对象都有多个属性，提取一部分属性组成一个新的数组（以下方法省略了遍历）

方法一：

const obj = {
    a:1,
    b:2,
    c:3,
    d:4,
};
const {a,b,c} = obj;
const obj1 = {a,b,c};
console.log(obj1) //{a:1,b:2,c:3}

方法二：（不需要的属性放前面，obj1就是剩下的）

const obj = {
    a:1,
    b:2,
    c:3,
    d:4,
};
const {d,...obj1} = obj
console.log(obj1) //{a:1,b:2,c:3}

方法三：

const obj2 = (({a, d, e}) => ({a, d, e}))(obj)

最基础写法：

let obj = {name: 'a', age: 19, sex: 'female'}
let obj2 = {
  name: obj.name,
  age: obj.age    
}

未验证方法：

const pick = (obj, arr) =>

    arr.reduce((iter, val) => (val in obj && (iter[val] = obj[val]), iter), {});

    

let obj2 = pick(obj, ['a', 'd', 'e'])

var obj = {
    a: 1,
    b: 2,
    c: 3,
    d: 4,
    e: 5
};
function extend(obj) {
    var o = {},
    attr = Array.prototype.slice.call(arguments).slice(1);
    attr.forEach(function(val, index) {
    if (val in obj) { o[val] = obj[val]; }
    });
    return o;
}
console.log(extend(obj, 'c', 'b')); //{ c: 3, b: 2 }