一、cloneDeep

      const { cloneDeep } = _

      const obj = {
        name: 'xx',
        arr: [1, 2, 3, [4, 5]],
        person: { name: 'yy' }
      }

      const obj1 = cloneDeep(obj)

手动实现：

      function cloneDeep(val) {
        if (val === null || typeof val !== 'object') return val
        var res = new val.constructor()
        for (var key in val) res[key] = cloneDeep(val[key]) // 递归调用
        return res
      }

这里没有对Set、Map、RegExp和循环引用做处理。另外，可以使用structuredClone进行深复制，这是一个比较新的全局方法

二、debounce

      var { debounce } = _

      window.addEventListener('resize', debounce(handle, 200))

      function handle() {
        console.log(document.documentElement.clientWidth)
      }

实现：

      function debounce(cb, delay) {
        var timer = null
        return function () {
          if (timer) clearTimeout(timer)
          var _this = this
          var _arguments = arguments
          timer = setTimeout(function () {
            cb.apply(_this, _arguments)
          }, delay)
        }
      }

三、throttle

      var { throttle } = _

      window.addEventListener('resize', throttle(handle, 200))

      function handle() {
        console.log(document.documentElement.clientWidth)
      }

通过定时器实现：

      function mythrottle(cb, delay) {
        var timer = null
        return function () {
          var _this = this
          var _arguments = arguments
          if (!timer) {
            timer = setTimeout(function () {
              cb.apply(_this, _arguments)
              clearTimeout(timer)
              timer = null
            }, delay)
          }
        }
      }

通过时间戳实现：

      function throttle(cb, delay) {
        var prevTime = Date.now()
        return function () {
          var curTime = Date.now()
          if (curTime - prevTime > delay) {
            cb.apply(this, arguments)
            prevTime = Date.now()
          }
        }
      }

四、curry

      var { curry } = _

      function sum(a, b, c) {
        return a + b + c
      }

      const currySum = curry(sum)

      console.log(currySum(1, 2, 3))
      console.log(currySum(1)(2, 3))
      console.log(currySum(1, 2)()()(3))

实现：

      function curry(cb, ...args) {
        if (args.length >= cb.length) {
          return cb(...args)
        }
        return (...rest) => {
          return curry(cb, ...args, ...rest)
        }
      }

五、数组对象去重

      var arr = [
        { id: 1, name: 'xx' },
        { id: 1, name: 'yy' },
        { id: 2, name: 'oo' },
        { id: 2, name: 'pp' },
        { id: 3, name: 'qq' }
      ]

      var newArr = uniqBy(arr, 'id')

实现：

      const uniqBy = (arr, property) => {
        const map = new Map()
        for (const item of arr) {
          if (!map.has(item[property])) map.set(item[property], item)
        }
        return [...map.values()]
      }

六、