ES10 ------ 扩展方法

  const result = Object.fromEntries([
        ['name','理工大学'],
        ['xueke','前端,java,大数据']
    ])
    console.log(result)

  const m = new Map()
    m.set('name','理工大学')
    const result = Object.fromEntries(m)
    console.log(result)

  const arr = Object.entries({
        name: '理工大学'
    })
    console.log(arr)

  let str = '   iloveyou   '
    console.log(str)
    console.log(str.trimStart())
    console.log(str.trimEnd())

  const arr = [1,2,3,4,[5,6]]
    console.log(arr.flat())

  const arr = [1,2,3,4,[5,6,[7,8,9]]]
    console.log(arr.flat())

  const arr = [1,2,3,4,[5,6,[7,8,9]]]
    // 参数为深度,是一个数字
    console.log(arr.flat(2))

  const arr = [1,2,3,4]
    const result = arr.map(item => item *10)
    console.log(result)

  // 创建 Symbol
    let s = Symbol('理工大学')
    console.log(s.description) // 理工大学