text: export const forEach = (arr, fn) => {
    if (!arr.length || !fn) return
    let i = -1
    let len = arr.length
    while (++i < len) {
      let item = arr[i]
      fn(item, i, arr)
    }
  }
  
  /**
   * @param {Array} arr1
   * @param {Array} arr2
   * @description 得到两个数组的交集, 两个数组的元素为数值或字符串
   */
  export const getIntersection = (arr1, arr2) => {
    let len = Math.min(arr1.length, arr2.length)
    let i = -1
    let res = []
    while (++i < len) {
      const item = arr2[i]
      if (arr1.indexOf(item) > -1) res.push(item)
    }
    return res
  }
  
  /**
   * @param {Array} arr1
   * @param {Array} arr2
   * @description 得到两个数组的并集, 两个数组的元素为数值或字符串
   */
  export const getUnion = (arr1, arr2) => {
    return Array.from(new Set([...arr1, ...arr2]))
  }
  
  /**
   * @param {Array} target 目标数组
   * @param {Array} arr 需要查询的数组
   * @description 判断要查询的数组是否至少有一个元素包含在目标数组中
   */
  export const hasOneOf = (targetarr, arr) => {
    return targetarr.some(_ => arr.indexOf(_) > -1)
  }
  
  /**
   * @param {String|Number} value 要验证的字符串或数值
   * @param {*} validList 用来验证的列表
   */
  export function oneOf (value, validList) {
    for (let i = 0; i < validList.length; i++) {
      if (value === validList[i]) {
        return true
      }
    }
    return false
  }
  
  /**
   * @param {Number} timeStamp 判断时间戳格式是否是毫秒
   * @returns {Boolean}
   */
  const isMillisecond = timeStamp => {
    const timeStr = String(timeStamp)
    return timeStr.length > 10
  }
  
  /**
   * @param {Number} timeStamp 传入的时间戳
   * @param {Number} currentTime 当前时间时间戳
   * @returns {Boolean} 传入的时间戳是否早于当前时间戳
   */
  const isEarly = (timeStamp, currentTime) => {
    return timeStamp < currentTime
  }
  
  /**
   * @param {Number} num 数值
   * @returns {String} 处理后的字符串
   * @description 如果传入的数值小于10，即位数只有1位，则在前面补充0
   */
  const getHandledValue = num => {
    return num < 10 ? '0' + num : num
  }
  
  /**
   * @param {Number} timeStamp 传入的时间戳
   * @param {Number} startType 要返回的时间字符串的格式类型，传入'year'则返回年开头的完整时间
   */
  const getDate = (timeStamp, startType) => {
    const d = new Date(timeStamp * 1000)
    const year = d.getFullYear()
    const month = getHandledValue(d.getMonth() + 1)
    const date = getHandledValue(d.getDate())
    const hours = getHandledValue(d.getHours())
    const minutes = getHandledValue(d.getMinutes())
    const second = getHandledValue(d.getSeconds())
    let resStr = ''
    if (startType === 'year') resStr = year + '-' + month + '-' + date + ' ' + hours + ':' + minutes + ':' + second
    else resStr = month + '-' + date + ' ' + hours + ':' + minutes
    return resStr
  }
  
  /**
   * @param {String|Number} timeStamp 时间戳
   * @returns {String} 相对时间字符串
   */
  export const getRelativeTime = timeStamp => {
    // 判断当前传入的时间戳是秒格式还是毫秒
    const IS_MILLISECOND = isMillisecond(timeStamp)
    // 如果是毫秒格式则转为秒格式
    if (IS_MILLISECOND) Math.floor(timeStamp /= 1000)
    // 传入的时间戳可以是数值或字符串类型，这里统一转为数值类型
    timeStamp = Number(timeStamp)
    // 获取当前时间时间戳
    const currentTime = Math.floor(Date.parse(new Date()) / 1000)
    // 判断传入时间戳是否早于当前时间戳
    const IS_EARLY = isEarly(timeStamp, currentTime)
    // 获取两个时间戳差值
    let diff = currentTime - timeStamp
    // 如果IS_EARLY为false则差值取反
    if (!IS_EARLY) diff = -diff
    let resStr = ''
    const dirStr = IS_EARLY ? '前' : '后'
    // 少于等于59秒
    if (diff <= 59) resStr = diff + '秒' + dirStr
    // 多于59秒，少于等于59分钟59秒
    else if (diff > 59 && diff <= 3599) resStr = Math.floor(diff / 60) + '分钟' + dirStr
    // 多于59分钟59秒，少于等于23小时59分钟59秒
    else if (diff > 3599 && diff <= 86399) resStr = Math.floor(diff / 3600) + '小时' + dirStr
    // 多于23小时59分钟59秒，少于等于29天59分钟59秒
    else if (diff > 86399 && diff <= 2623859) resStr = Math.floor(diff / 86400) + '天' + dirStr
    // 多于29天59分钟59秒，少于364天23小时59分钟59秒，且传入的时间戳早于当前
    else if (diff > 2623859 && diff <= 31567859 && IS_EARLY) resStr = getDate(timeStamp)
    else resStr = getDate(timeStamp, 'year')
    return resStr
  }
  
  /**
   * @returns {String} 当前浏览器名称
   */
  export const getExplorer = () => {
    const ua = window.navigator.userAgent
    const isExplorer = (exp) => {
      return ua.indexOf(exp) > -1
    }
    if (isExplorer('MSIE')) return 'IE'
    else if (isExplorer('Firefox')) return 'Firefox'
    else if (isExplorer('Chrome')) return 'Chrome'
    else if (isExplorer('Opera')) return 'Opera'
    else if (isExplorer('Safari')) return 'Safari'
  }
  
  /**
   * @description 绑定事件 on(element, event, handler)
   */
  export const on = (function () {
    if (document.addEventListener) {
      return function (element, event, handler) {
        if (element && event && handler) {
          element.addEventListener(event, handler, false)
        }
      }
    } else {
      return function (element, event, handler) {
        if (element && event && handler) {
          element.attachEvent('on' + event, handler)
        }
      }
    }
  })()
  
  /**
   * @description 解绑事件 off(element, event, handler)
   */
  export const off = (function () {
    if (document.removeEventListener) {
      return function (element, event, handler) {
        if (element && event) {
          element.removeEventListener(event, handler, false)
        }
      }
    } else {
      return function (element, event, handler) {
        if (element && event) {
          element.detachEvent('on' + event, handler)
        }
      }
    }
  })()
  
  /**
   * 判断一个对象是否存在key，如果传入第二个参数key，则是判断这个obj对象是否存在key这个属性
   * 如果没有传入key这个参数，则判断obj对象是否有键值对
   */
  export const hasKey = (obj, key) => {
    if (key) return key in obj
    else {
      let keysArr = Object.keys(obj)
      return keysArr.length
    }
  }
  
  /**
   * @param {*} obj1 对象
   * @param {*} obj2 对象
   * @description 判断两个对象是否相等，这两个对象的值只能是数字或字符串
   */
  export const objEqual = (obj1, obj2) => {
    const keysArr1 = Object.keys(obj1)
    const keysArr2 = Object.keys(obj2)
    if (keysArr1.length !== keysArr2.length) return false
    else if (keysArr1.length === 0 && keysArr2.length === 0) return true
    /* eslint-disable-next-line */
    else return !keysArr1.some(key => obj1[key] != obj2[key])
  }
  
  /**
   * @param {*} date1 开始日期
   * @param {*} date2 结束日期
   * @description 计算两个日期相差天数
   */
  export const getDaysBetween = (date1, date2) => {
    var startDate = Date.parse(date1)
    var endDate = Date.parse(date2)
    var days = (endDate - startDate) / (1 * 24 * 60 * 60 * 1000)
    return days
  }
  
  /**
   * @param {*} date1 日期1
   * @param {*} date2 日期2
   * @description 判断日期是否同一周内
   */
  export const isSameWeek = (date1, date2) => {
    var oneDayTime = 1000 * 60 * 60 * 24
    var oldCount = parseInt(date1.getTime() / oneDayTime)
    var nowOther = parseInt(date2.getTime() / oneDayTime)
    return parseInt((oldCount + 4) / 7) === parseInt((nowOther + 4) / 7)
  }
  