在addEventListener或element.on附加的事件处理程序中返回false` [英] `return false` in an event handler attached by addEventListener or element.on*

问题描述

是的，让我们先解决这个问题。是的，我想隐藏上下文菜单。不，我不是想阻止某人从我的页面上取消内容。它的用途是输入浏览器中的游戏，它将仅限于网页上的特定区域。

Right let’s get this out the way first. Yes, I want to hide the context menu. No, I’m not trying to prevent someone lifting content off my page. Its intended use is input for an in-browser game and it will be limited to a specific area on the webpage.

从意识形态转向技术...... / p>

Moving from the ideological to the technical...

var mouse_input = function (evt) {
    // ...
    return false;
}

document.onmousedown = mouse_input; // successful at preventing the menu.
document.addEventListener('mousedown', mouse_input, true); // unsuccessful

有人可以向我解释为什么 addEventListener 版本无法停止上下文菜单的触发？我在 Safari 的 Web Inspector 中看到的唯一区别是 document.onmousedown 有一个 isAttribute 值为true，而 addEventListener 版本的值与false相同。

Could someone explain to me why the addEventListener version is unable to stop the context menu from firing? The only difference I was able to see in Safari's Web Inspector was that document.onmousedown had a isAttribute value that was true whilst the addEventListener version had the same value as false.

推荐答案

所以我的无用搜索突然变得富有成效。

So my unfruitful search suddenly became fruitful.

var mouse_input = function (evt) {
    evt.preventDefault();
}

document.addEventListener('contextmenu', mouse_input, false);

适用于 Safari ， Firefox ，歌剧。 preventDefault（）停止发生通常的操作。我不得不改变为了适应 Safari 而被监听的事件，无论如何它更合乎逻辑。更多信息：实现 EventListener 不应返回值，因此 return false 无效。

Works for Safari, Firefox, Opera. preventDefault() stops the usual actions from happening. I had to change the event that was listened for to accommodate for Safari and it is more logical anyway. Further information: functions that implement EventListener shouldn’t return values so return false had no effect.

这篇关于在addEventListener或element.on附加的事件处理程序中返回false`的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！