我对React、useEffect和向事件侦听器添加回调函数感到困惑。这些侦听器被注册到Google Publisher Tag事件,我试图获得结果,在那里我可以使用传递的参数(在我的示例代码中为display
)和回调函数中的事件对象。
<div id="app"></div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/18.2.0/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/18.2.0/umd/react-dom.production.min.js"></script>
<script src="https://securepubads.g.doubleclick.net/tag/js/gpt.js"></script>````
const { useEffect } = React;
const slotOnloadCallback = (display, event) => {
const { slot } = event;
console.log(`callback called for slot ${slot.getSlotElementId()} - display: ${display}`);
};
const create = (id, display) => {
window.googletag = window.googletag || {cmd: []};
window.googletag.cmd.push(function() {
const slot = window.googletag.defineSlot('/1234567/example', [728, 90], id);
slot.addService(googletag.pubads());
window.googletag.pubads().enableSingleRequest();
window.googletag.enableServices();
});
window.googletag.pubads().addEventListener("slotOnload", slotOnloadCallback.bind(null, display));
window.googletag.cmd.push(function() {
window.googletag.display(id);
});
}
const Ad = (props) => {
const { id, display } = props;
console.log(`Ad ${id}: Rendering`);
useEffect(() => {
console.log(`Ad ${id}: Mounted`);
create(id, display)
}, []);
return (
<div id={id}></div>
);
};
function App() {
return (
<div>
<Ad
id="slot-1"
display="full"
/>
<p>...</p>
<Ad
id="slot-2"
display="partial"
/>
</div>
)
}
ReactDOM.render(<App />, document.querySelector("#app"));
事件侦听器正在工作,但当我将所需的变量绑定到回调时,回调最终会被触发多次(* 呈现的Ad组件的数量)。我想我理解将变量绑定到一个函数使其唯一,因此可以多次注册到一个侦听器,但我认为使用useEffect绕过了这个问题。:(
我得到输出:
"Ad slot-1: Rendering"
"Ad slot-2: Rendering"
"Ad slot-1: Mounted"
"Ad slot-2: Mounted"
"callback called for slot slot-1 - display: full"
"callback called for slot slot-1 - display: partial"
"callback called for slot slot-2 - display: full"
"callback called for slot slot-2 - display: partial"
.其中我很困惑slot-1
是如何接收partial
的。
有没有一种方法可以确保事件侦听器只在每个组件中触发一次?我尝试过将回调定义移到组件的useEffect
块中,也尝试过在App
中定义它并将其作为prop传递给组件,但这些都有相同的结果。
任何帮助将非常感谢!
1条答案
按热度按时间8ehkhllq1#
useEffect
在开发模式下运行两次。你得注意移除监听器