es6 lambda对数组和对象的操作

es6一些常用的，好用的操作

源数据

let people = [
        {id: 1, name: "a", age: 12}, 
        {id: 2, name: "b", age: 13}, 
        {id: 3, name: "c", age: 14}, 
        {id: 4, name: "d", age: 15}, 
        {id: 5, name: "e", age: 16},
        {id: 6, name: "f", age: 16}
    ];

创建新的对象

let kids = [];
people.forEach(person => {
    if (person.age < 15) {
        kids.push({
            id: person.id,
            name: person.name
        })
    }
});
console.log("kids",kids);//[{id: 1, name: "a"},{id: 2, name: "b"},{id: 3, name: "c"}]

重写forEach示例重写（推荐）

let kids2 = people
    .filter(person => person.age < 15)
    .map(person => ({
        id: person.id,
        name: person.name
    }));
console.log("kids2",kids2);

取出一个属性

let arrnew = []
people.forEach(e => {
    arrnew.push(e.name)
})
console.log("arrnew",arrnew); //["a", "b", "c", "d", "e", "f"]

一个属性去重

let arrnew = ["a", "a", "c", "c", "e", "f"]
console.log("arrnew",arrnew); 
let arrnew2 = Array.from(new Set(arrnew))
console.log("arrnew2",arrnew2); //["a", "c", "e", "f"]

一个数组根据属性去重

    let people = [
        {id: 1, name: "a", age: 12}, 
        {id: 2, name: "a", age: 13}, 
        {id: 3, name: "d", age: 14}, 
        {id: 4, name: "d", age: 15}, 
        {id: 5, name: "e", age: 16},
        {id: 6, name: "f", age: 16}
    ];
	
	let arr1 = people.filter((obj, pos, arr)=>{
		return arr.map(mapObj =>mapObj['name']).indexOf(obj['name']) === pos;
	});
	console.log(arr1); //[{id: 1, name: "a", age: 12},{id: 3, name: "d", age: 14},{id: 5, name: "e", age: 16},{id: 6, name: "f", age: 16}]

用map取出一个属性（推荐）

let arrnew1 = people.map((item,index) => {
      return item.name;
 })
 console.log("arrnew1",arrnew1); //["a", "b", "c", "d", "e", "f"]

取出一个属性变成对象

let arrnew2 = people.map((item,index) => {
      return Object.assign({},{'name':item.name})
 })
console.log("arrnew2",arrnew2); //[0: {name: "a"},{name: "b"},{name: "c"},{name: "d"},{name: "e"},{name: "f"}]

返回项参与的表达式值

let numbers = [1, 2, 3];
let numbers_map = numbers.map(number => number * 6); 
console.log("numbers_map",numbers_map);//[6,12,18]

返回满足条件的项

let numbers = [1, 2, 3];
let numbers_filter = numbers.filter(number => number % 2 === 0); 
console.log("numbers_filter",numbers_filter);//[2]