我正在用纯 Javascript 创建自定义事件并将其附加到 DOM 元素。该元素具有针对同一事件的多个事件监听器。我写的代码是:
var element = document.getElementById('demo');
element.addEventListener("myCustomEvent", function(e) {
console.log("myCustomEvent first handler triggered");
});
element.addEventListener("myCustomEvent", function(e) {
console.log("myCustomEvent second handler triggered");
e.data['otherKey'] = 'other value';
return e.data;
});
// Trigger the event
var event = new CustomEvent("myCustomEvent", {
data: {
firstKey: 'first Value'
}
});
element.dispatchEvent(event);
现在我想要的是,从最后一个事件处理程序中获取数据,如下所示:var modifiedData = element.dispatchEvent(event);
虽然我知道上面的行可能不正确,但我想要这样的东西。如果我使用 jQuery,那么很简单,比如 $.triggerHandler
我可以使用它遍历特定事件的所有监听器,并给出最后一个处理程序的返回值(如果有)。但我想用纯 Javascript 来做。这种事情有什么解决办法吗?
最佳答案
只需使用 detail
属性,它应该像您期望的那样工作:
var element = document.getElementById('demo');
element.addEventListener("myCustomEvent", function(e) {
console.log("myCustomEvent first handler triggered");
e.detail.otherKey = 'second value';
});
element.addEventListener("myCustomEvent", function(e) {
console.log("myCustomEvent second handler triggered");
console.log(e.detail);
});
// Trigger the event
var event = new CustomEvent("myCustomEvent", {
detail: {
firstKey: 'first Value'
}
});
element.dispatchEvent(event);
<div id="demo"></div>
根据评论,这里有一个想法,您可以如何实现您希望做的事情:
var element = document.getElementById('demo');
var originalFun = element.__proto__.addEventListener.bind(element);
var handlers = {};
var wrapperFun = function(e) {
if (e.type in handlers) {
var data = e.detail;
handlers[e.type].forEach(function(fun){
data = fun(data) || data;
});
}
};
element.__proto__.addEventListener = function(type, handler) {
if (typeof handlers[type] === 'undefined') {
handlers[type] = [];
originalFun(type, wrapperFun);
}
handlers[type].push(handler);
};
element.addEventListener("myCustomEvent", function(e) {
console.log("myCustomEvent first handler triggered");
e.otherKey = 'second value';
return e;
});
element.addEventListener("myCustomEvent", function(e) {
console.log("myCustomEvent second handler triggered");
console.log(e);
});
// Trigger the event
var event = new CustomEvent("myCustomEvent", {
detail: {
firstKey: 'first Value'
}
});
element.dispatchEvent(event);
<div id="demo"></div>
关于javascript - 使用纯 Javascript 从自定义事件处理程序收集数据,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/42204621/