学习笔记---操作数组之遍历循环

 定义数组

var userList = [
  {
    name: '张三',
    age: 23,
    job: 'tester'
  },
  {
    name: '李四',
    age: 20,
    job: 'programmer'
  },
  {
    name: '王五',
    age: 45,
    job: 'programmer'
  },
  {
    name: '赵六',
    age: 34,
    job: 'tester'
  }
]

一、.forEach() --- 操作数组

var Users = []
this.userList.forEach(item => {
  Users.push(item.name) // 获取成员姓名
})

二、.map() --- 操作数组

var Users = this.userList.map(item => item.name)

三、.filter() --- 过滤元素

var Users = this.userList.filter(item => item.name === '张三') // 筛选出满足特定条件的数组

四、.reduce() --- 累加

reduceM (total, index) {
    return total + index
}

var ages = [1, 2, 3, 4]
var Users = ages.reduce(this.reduceM, 0) // 调用累加函数

 五、find() --- 查找元素

let users = userList.find(element, index, arr) // element:当前元素，index:当前元素得索引值，arr:整个数组

let users = userList.find(user => user.name === '张三') // 输出当前元素

let users = userList.findIndex(user => user.name === '张三') // 输出当前元素索引值

六、some() --- 判断

let users = userList.some(user => user.age > 35) // 任一元素满足条件则返回true，所有都不满足则返回false

七、every() --- 判断

let users = userList.every(user => user.age > 35) // 所有元素满足条件则返回true，任一不满足则返回false