前端面试题 6

题目一
去除数组中的重复值

    const arr = [1, 2, 2, 1, 3]
    const set = new Set(arr)
    console.log([...set]) // [1, 2, 3]
    console.log(arr) // [1, 2, 2, 1, 3]

---

题目二

    const createInfo = ({ email, address = {} }) => {
      const validEmail = /^[a-zA-Z0-9_-]+@[a-zA-Z0-9_-]+(\.[a-zA-Z0-9_-]+)+$/.test(email)
      if (!validEmail) throw new Error("invalid email")
      return {
        email,
        address: address ? address : null
      }
    }
    const email = 'cc@163.com'
    const email2 = '@163.com'
    const address = '北京'
    const result = createInfo({ email })
    console.log(result)
    const result2 = createInfo({ email, address })
    console.log(result2)
    const result3 = createInfo({ email2 })
    console.log(result3)

---

题目三

    console.log([] ? 1 : 2) // 1
    console.log({} ? 1 : 2) // 1
    console.log("1" ? 1 : 2) // 1
    console.log("2" ? 1 : 2) // 1
    console.log(" " ? 1 : 2) // 1
    console.log(NaN ? 1 : 2) // 2 
    console.log(undefined ? 1 : 2) // 2
    console.log(null ? 1 : 2) // 2
    console.log("" ? 1 : 2) // 2