使“scrollLeft” /" scrollTop"更改不会触发滚动事件侦听器 [英] Make "scrollLeft" / "scrollTop" changes not trigger scroll event listener

问题描述

目前，我的程序处于侦听用户滚动某个元素的位置，但有时也会自动滚动此元素。 （不是一个渐进的，漂亮的滚动，而是一个瞬间的跳跃，这是有道理的，我发誓。）

Currently my program is in a spot where it both listens for the user to scroll a certain element, but also, at times, automatically scrolls this element by itself. (Not a gradual, pretty scroll, but an instant jump. It makes sense in context, I swear.)

有没有办法让scroll事件不会触发if滚动是通过设置scrollLeft或scrollTop完成的？我的第一个想法是一个基本的开关，比如：

Is there a way to make the scroll event not trigger if the scrolling was done by setting scrollLeft or scrollTop? My first thought was a basic switch, like:

ignoreScrollEvents = true;
element.scrollLeft = x;
ignoreScrollEvents = false;

function onScroll() {
  if(ignoreScrollEvents) return false;
}

但是由于事件不会立即触发（oops，duhh），那不是一个可行的解决方案。我还可以尝试其他类型的答案吗？我也使用jQuery，如果这有帮助的话。

but since events don't trigger immediately (oops, duhh), that's not a workable solution. What other sort of answers could I try? I'm also using jQuery, if that helps anything.

推荐答案

最简单的通用方法？只需重置事件处理程序中的标志即可。您需要首先检查是否实际更改了值，否则将不会触发事件 - 如 Rodrigo笔记，这里的一个很好的做法是把这个分解成所谓的setter功能：

Easiest generic method? Just reset the flag in the event handler. You'll want to check first if you're actually changing the value, as otherwise an event won't be fired - as Rodrigo notes, a good practice here is to factor this out into so-called "setter" functions:

function setScrollLeft(x)
{
  if ( element.scrollLeft != x )
  {
    ignoreScrollEvents = true;
    element.scrollLeft = x;
  }
} 

...

function onScroll() 
{
  var ignore = ignoreScrollEvents;
  ignoreScrollEvents = false;

  if (ignore) return false;

  ...
}

但是，根据您的需要，您可能已经在某处存储滚动位置;如果是这样，只需更新并检查该标志即可。例如：

But, depending on your needs, you may already be storing the scroll position somewhere; if so, just update and check that as your flag. Something like:

element.scrollLeft = currentScrollLeft = x;

...

function onScroll() 
{
  // retrieve element, etc... 

  if (element.scrollLeft == currentScrollLeft) return false;

  ...
}

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