如何在javascript中清除间隔?

问题描述

我的代码:

$(function() {

     $('a.startSlideshow').click(function() {
          startSlideShow = window.setInterval(function() { slideSwitch() }, 1000);
     });


     $('a.next').click(function() {
          if (startSlideShow) {
               clearInterval(startSlideShow);
          }
          nextSlide();
     });

});

我的意图:

如果用户单击startSlideshow链接，则每1秒钟执行一次幻灯片显示功能.

If a user clicks the startSlideshow link the slideshow function is executed every 1 seconds.

如果用户单击了下一个链接，则如果幻灯片放映功能已被执行，则幻灯片放映功能将停止.

If the user clicks the next link, the slideshow function is stopped IF IT HAS ALREADY BEEN EXECUTED.

为了能够检测到这一点，我将设置的间隔存储为变量.但是，当我检查它时:

To be able to detect this, I stored the set interval as a variable. However when I check for it:

          if (startSlideShow) {
               clearInterval(startSlideShow);
          }

它不起作用.现在，如果在单击下一步"之前单击开始幻灯片放映"链接，则我的代码有效.但是，如果幻灯片功能从未启动过(即我从没有先单击该链接，而是从头开始单击了下一步)，则代码将失败.

It doesn't work. Right now my code works if I click on the start slideshow link before clicking next. But if the slideshow function was never started (i.e. I never clicked that link first but clicked next from the start) the code fails.

基本上，这导致未定义startSlideshow var时由于某些原因导致代码中断:

basically this is causing the code to break for some reason when startSlideshow var hasn't been defined:

      if (startSlideShow) {
           clearInterval(startSlideShow);
      }

我确实尝试了其他方法来检查该变量是否已设置，但是都失败了.该如何解决?

I did try other ways of checking to see if that variable has been set, but all failed. How to solve this?

推荐答案

在第一个处理程序之前声明startSlideShow:

Declare startSlideShow before your first handler:

var startSlideShow = null;

并稍后清除它:

if (startSlideShow) {
    window.clearInterval(startSlideShow);
    startSlideShow = null;
}

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