js使用cookie存取值

设置cookie

function setCookie (name, value) {
  if (value) {
    var Days = 365
    var exp = new Date()
    exp.setTime(exp.getTime() + Days * 24 * 60 * 60 * 1000)
    document.cookie = name + '=' + escape(value) + ';expires=' + exp.toGMTString()
  }
}

获取cookie

function getCookie (name) {
  if (document.cookie.length > 0) {
    var begin = document.cookie.indexOf(name + '=')
    if (begin !== -1) {
      begin += name.length + 1 // cookie值的初始位置
      var end = document.cookie.indexOf(';', begin) // 结束位置
      if (end === -1) {
        end = document.cookie.length // 没有;则end为字符串结束位置
      }
      return unescape(document.cookie.substring(begin, end))
    }
  }
  return null
  // cookie不存在返回null
}

清除某个cookie值

function delCookie (name) {
  var exp = new Date()
  exp.setTime(exp.getTime() - 1)
  var cval = setCookie(name)
  if (cval && cval != null) {
    document.cookie = name + '=' + cval + ';expires=' + exp.toGMTString()
  }
}

清除所有cookie

function clearCookie () {
  var keys = document.cookie.match(/[^ =;]+(?=\=)/g)
  if (keys) {
    for (var i = keys.length; i--;) {
      document.cookie = keys[i] + '=0;expires=' + new Date(0).toUTCString()
    }
  }
}