JavaScript，停止其他事件侦听器 [英] JavaScript, stop additional event listeners

问题描述

想象一下，我有这样的代码：

Imagine I have this code:

var myFunc1 = function(event) {
    alert(1);
}
var myFunc2 = function(event) {
    alert(2);
}

element.addEventListener('click', myFunc1);
element.addEventListener('click', myFunc2);

当点击事件被触发时，调用myFunc1，然后调用myFunc2。但是，如果满足myFunc1中的某些条件，我如何（如果可能的话）停止调用myFunc2？ event.stopPropagation（）不是解决方案，因为这不是事件捕获/冒泡问题。

When the click event is fired myFunc1 is called, then myFunc2. But how do I (if at all possible) stop myFunc2 from being called if some condition in myFunc1 is met? event.stopPropagation() is not the solution, as this is not an event capturing/bubbling problem.

谢谢。

推荐答案

还有一个问题：执行事件监听器的顺序是未定义的。您需要自己处理事件调度以解决此问题，这导致我们对llimllib建议的一些变体。

There's a further problem: the order that event listeners are executed is undefined. You'll need to handle event dispatch on your own to get around this, which leads us to some variant of llimllib's suggestion.

function dispatchSleightEvent(evt) {
    var listeners = evt.currentTarget.sleightListeners[evt.type];
    // can't use for-in because enumeration order is implementation dependent
    for (var i=0; i<listeners.length; ++i) {
       if (listeners[i]) {
         if (! listeners[i].call(evt.currentTarget, evt)) {
           return false;
         }
       }
    }
    return true;
}

function mixinSleightTarget(obj) {
  if (! obj.sleightListeners) {
    obj.sleightListeners = {}
    obj.addSleightListener = function(type, listener) {
        if (!this.sleightListeners[type]) {
            this.sleightListeners[type] = [];
            this.addEventListener(type, dispatchSleightEvent);
        }
        if (!this.sleightListeners[type+listener] {
          this.sleightListeners[type+listener] = this.sleightListeners[type].length;
          this.sleightListeners[type].push(listener);
        }
    }
    obj.removeSleightListener = function(type, listener) {
        if (this.sleightListeners[type+listener] {
          delete this.sleightListeners[type][this.sleightListeners[type+listener]];
          delete this.sleightListeners[type+listener];
        }          
    }
  }
}

此代码完全未经测试。要在单个目标上停止事件调度，一个事件监听器返回 false 。如果你想要更多的数据隐藏，你可以从功能编程的角度重写上述内容，尽管这可能会引入内存泄漏。

This code is completely untested. To stop event dispatch while on a single target, an event listener returns false. If you want more data hiding, you can rewrite the above from a functional programming standpoint, though this might introduce memory leaks.

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