js map 、filter 、forEach 的用法

1. map 函数

// 添加index 
let origin_arr = [
		{"name": "zhangsan", "sex": "man"},
		{"name": "lisi", "sex": "man"},
		{"name": "wangwu", "sex": "feman"}
	 ]

let new_arr = origin_arr.map((item, index) => {
	return {
		...item,
		index: index + 1
	}
})

2. filter 函数

// 只取数组中为man的数据
let origin_arr = [
		{"name": "zhangsan", "sex": "man"},
		{"name": "lisi", "sex": "man"},
		{"name": "wangwu", "sex": "feman"}
	 ]

let new_arr = origin_arr.filter(item => {
	return item["sex"] == "man"
})

3. forEach函数

// 只取数组中为man的数据
let origin_arr = [
		{"id": 1, "name": "zhangsan", "sex": "man"},
		{"id": 2, "name": "lisi", "sex": "man"},
		{"id": 3, "name": "wangwu", "sex": "feman"}
	 ]

origin_arr.forEach(item => {
	item["id"] += 1
})