未捕获的类型错误：无法读取 null 的属性“2”答案

【问题标题】：Uncaught TypeError: Cannot read property '2' of null未捕获的类型错误：无法读取 null 的属性“2”
【发布时间】：2020-08-02 16:52:13
【问题描述】：

我有 JS 计时器，但我的 cookie 脚本给出了这个错误：

未捕获的类型错误：无法读取 null 的属性“2”

该错误仅在重新加载页面时出现。所以我假设 cookie 在那里，但我找不到另一个问题。错误来自这一行：deadline = document.cookie.match(/(^|;)myClock=([^;]+)/)[2];

这里是 HTML

<div id="clockdiv">
I'm a timer
    <span class="days hide"></span>
    <span class="hours hide"></span>
    <span class="minutes"></span> : 
    <span class="seconds"></span>
</div>

这里是JS

function getTimeRemaining(endtime) {
  const total = Date.parse(endtime) - Date.parse(new Date());
  const seconds = Math.floor((total / 1000) % 60);
  const minutes = Math.floor((total / 1000 / 60) % 60);
  const hours = Math.floor((total / (1000 * 60 * 60)) % 24);
  const days = Math.floor(total / (1000 * 60 * 60 * 24));
  
  return {
    total,
    days,
    hours,
    minutes,
    seconds
  };
}

function initializeClock(id, endtime) {
  const clock = document.getElementById(id);
  const daysSpan = clock.querySelector('.days');
  const hoursSpan = clock.querySelector('.hours');
  const minutesSpan = clock.querySelector('.minutes');
  const secondsSpan = clock.querySelector('.seconds');

  function updateClock() {
    const t = getTimeRemaining(endtime);

    daysSpan.innerHTML = t.days;
    hoursSpan.innerHTML = ('0' + t.hours).slice(-2);
    minutesSpan.innerHTML = ('0' + t.minutes).slice(-2);
    secondsSpan.innerHTML = ('0' + t.seconds).slice(-2);

    if (t.total <= 0) {
      clearInterval(timeinterval);
    }
  }

  updateClock();
  const timeinterval = setInterval(updateClock, 1000);
}

//const timeInMinutes = 8;
//const currentTime = Date.parse(new Date());
let deadline;

// if there's a cookie with the name myClock, use that value as the deadline
if(document.cookie && document.cookie.match('myClock')){
  // get deadline value from cookie
  deadline = document.cookie.match(/(^|;)myClock=([^;]+)/)[2];
} else {
  // otherwise, set a deadline 10 minutes from now and 
  // save it in a cookie with that name

  // create deadline 10 minutes from now
  const timeInMinutes = 8;
  const currentTime = Date.parse(new Date());
  deadline = new Date(currentTime + timeInMinutes*60*1000);

  // store deadline in cookie for future reference
  document.cookie = 'myClock=' + deadline + '; path=/; domain=.codepen.io';
}
initializeClock('clockdiv', deadline);

【问题讨论】：

我建议使用现成的函数来处理 Cookie。例如 w3schools.com/js/js_cookies.asp 看起来应该可以工作 jsfiddle.net/vyspiansky/po2zw4um
@IhorVyspiansky 谢谢。但是这行代码我仍然得到同样的错误：deadline = document.cookie.match(/(^|;)myClock=([^;]+)/)[2]; （刷新页面时）
您是否尝试使用 w3schools 函数 deadline = getCookie('myClock') 而不是 deadline = document.cookie.match(/(^|;)myClock=([^;]+)/)[2];？

标签： javascript cookies session-cookies

【解决方案1】：

尝试使用现成的 Cookie 函数，例如，从这里http://w3schools.com/js/js_cookies.asp

所以

deadline = document.cookie.match(/(^|;)myClock=([^;]+)/)[2];

可以替换为

deadline = getCookie('myClock');

看看这里http://jsfiddle.net/vyspiansky/po2zw4um

【讨论】：