滚动到反应视图中
我正在制作一个简单的反应应用程序，其中有两个不同的div's..
具有选择输入和选定列表的一个，
<div id="container">
<div className="_2iA8p44d0WZ">
<span className="chip _7ahQImy">Item One</span>
<span className="chip _7ahQImy">Item Two</span>
<span className="chip _7ahQImy">Item Three</span>
<span className="chip _7ahQImy">Item Four</span>
<span className="chip _7ahQImy">Item Five</span>
<input
type="text"
className="searchBox"
id="search_input"
placeholder="Select"
autoComplete="off"
value=""
/>
</div>
</div>
另一个会将所选选项列出为fieldset，
<div>
{selectedElements.map((item, i) => (
<div key={i} className="selected-element" ref={scrollDiv}>
<fieldset>
<legend>{item}</legend>
</fieldset>
</div>
))}
</div>
基于这个解决方案，我已添加createRef到所选元素，例如，
<div key={i} className="selected-element" ref={scrollDiv}>
</div>
然后我采用 Javascript 查询方法来获取 DOM 元素，例如，
const chipsArray = document.querySelectorAll("#container > div > .chip");
向所有元素添加了单击事件侦听器，例如，
chipsArray.forEach((elem, index) => {
elem.addEventListener("click", scrollSmoothHandler);
});
然后scrollSmoothHandler就像，
const scrollDiv = createRef();
const scrollSmoothHandler = () => {
console.log(scrollDiv.current);
if (scrollDiv.current) {
scrollDiv.current.scrollIntoView({ behavior: "smooth" });
}
};
但这并没有按预期工作。
森栏浏览 159回答 1
1回答
-
弑天下
问题React.createRef实际上只在基于类的组件中有效。如果在功能组件主体中使用，则将在每个渲染周期重新创建引用。不要使用 DOM 查询选择器将onClick侦听器附加到 DOM 元素。这些存在于外部反应，您需要记住清理它们（即删除它们），这样就不会出现内存泄漏。使用 React 的onClickprop。映射后，您将相同的selectedElements引用附加到每个元素，因此最后一组是您的 UI 获取的元素。解决方案在功能组件主体中使用React.useRef来存储反应引用数组，以附加到要滚动到视图中的每个元素。scrollSmoothHandler将直接附加到每个span的onClick支柱上。将 1. 中创建的引用数组中的每个引用附加到要滚动到的每个映射字段集。代码import React, { createRef, useRef } from "react";import { render } from "react-dom";const App = () => { const selectedElements = [ "Item One", "Item Two", "Item Three", "Item Four", "Item Five" ]; // React ref to store array of refs const scrollRefs = useRef([]); // Populate scrollable refs, only create them once // if the selectedElements array length is expected to change there is a workaround scrollRefs.current = [...Array(selectedElements.length).keys()].map( (_, i) => scrollRefs.current[i] ?? createRef() ); // Curried handler to take index and return click handler const scrollSmoothHandler = (index) => () => { scrollRefs.current[index].current.scrollIntoView({ behavior: "smooth" }); }; return ( <div> <div id="container"> <div className="_2iA8p44d0WZ"> {selectedElements.map((el, i) => ( <span className="chip _7ahQImy" onClick={scrollSmoothHandler(i)} // <-- pass index to curried handler > {el} </span> ))} <input type="text" className="searchBox" id="search_input" placeholder="Select" autoComplete="off" value="" /> </div> </div> <div> {selectedElements.map((item, i) => ( <div key={i} className="selected-element" ref={scrollRefs.current[i]} // <-- pass scroll ref @ index i > <fieldset> <legend>{item}</legend> </fieldset> </div> ))} </div> </div> );};解决方案#2由于您无法更新divwith中的任何元素id="container"，并且所有onClick处理程序都需要通过查询 DOM 来附加，因此您仍然可以使用柯里化scrollSmoothHandler回调并将索引包含在范围内。您需要一个钩子来在初始渲染后useEffect查询 DOM ，以便安装跨度，并需要一个钩子来存储“已加载”状态。该状态是触发重新渲染并重新包含在回调中所必需的。useStatescrollRefsscrollSmoothHandlerconst App = () => { const selectedElements = [ "Item One", "Item Two", "Item Three", "Item Four", "Item Five" ]; const [loaded, setLoaded] = useState(false); const scrollRefs = useRef([]); const scrollSmoothHandler = (index) => () => { scrollRefs.current[index].current.scrollIntoView({ behavior: "smooth" }); }; useEffect(() => { const chipsArray = document.querySelectorAll("#container > div > .chip"); if (!loaded) { scrollRefs.current = [...Array(chipsArray.length).keys()].map( (_, i) => scrollRefs.current[i] ?? createRef() ); chipsArray.forEach((elem, index) => { elem.addEventListener("click", scrollSmoothHandler(index)); }); setLoaded(true); } }, [loaded]); return ( <div> <div id="container"> <div className="_2iA8p44d0WZ"> <span className="chip _7ahQImy">Item One</span> <span className="chip _7ahQImy">Item Two</span> <span className="chip _7ahQImy">Item Three</span> <span className="chip _7ahQImy">Item Four</span> <span className="chip _7ahQImy">Item Five</span> <input type="text" className="searchBox" id="search_input" placeholder="Select" autoComplete="off" value="" /> </div> </div> <div> {selectedElements.map((item, i) => ( <div key={i} className="selected-element" ref={scrollRefs.current[i]}> <fieldset> <legend>{item}</legend> </fieldset> </div> ))} </div> </div> );};
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JavaScript