我使用Typescript与React。我有麻烦理解如何使用参考，以获得静态类型和智能感知的反应节点引用的参考。我的代码如下。
import * as React from 'react';
interface AppState {
count: number;
}
interface AppProps {
steps: number;
}
interface AppRefs {
stepInput: HTMLInputElement;
}
export default class TestApp extends React.Component<AppProps, AppState> {
constructor(props: AppProps) {
super(props);
this.state = {
count: 0
};
}
incrementCounter() {
this.setState({count: this.state.count + 1});
}
render() {
return (
<div>
<h1>Hello World</h1>
<input type="text" ref="stepInput" />
<button onClick={() => this.incrementCounter()}>Increment</button>
Count : {this.state.count}
</div>
);
}}
反应。createRef(类比较)
class ClassApp extends React.Component {
inputRef = React.createRef<HTMLInputElement>();
render() {
return <input type="text" ref={this.inputRef} />
}
}
反应。useRef(钩子/函数比较)
a) Use readonly refs for React-managed DOM nodes:
const FunctionApp = () => {
// note the passed-in `null` arg ----------------v
const inputRef = React.useRef<HTMLInputElement>(null)
return <input type="text" ref={inputRef} />
}
inputRef。通过将Current属性的值初始化为null, Current属性变为只读属性。
b) Use
可变参
for arbitrary stored values akin to instance variables:
const FunctionApp = () => {
const renderCountRef = useRef(0)
useEffect(() => {
renderCountRef.current += 1
})
// ... other render code
}
注意:在这种情况下不要初始化useRef为null——它会使renderCountRef类型为只读(参见示例)。如果你需要提供null作为初始值，这样做:
const renderCountRef = useRef<number | null>(null)
回调引用(两个)
// Function component example, class analogue
const FunctionApp = () => {
const handleDomNodeChange = (domNode: HTMLInputElement | null) => {
// ... do something with changed dom node.
}
return <input type="text" ref={handleDomNodeChange} />
}
注意:字符串引用被认为是遗留的，在此回答的范围内被省略。
操场上的样品
由于缺乏完整的示例，下面是我的小测试脚本，用于在使用React和TypeScript时获取用户输入。部分基于其他评论和此链接https://medium.com/@basarat/strong -typed-refs-for-react-typescript-9a07419f807#.cdrghertm
/// <reference path="typings/react/react-global.d.ts" />
// Init our code using jquery on document ready
$(function () {
ReactDOM.render(<ServerTime />, document.getElementById("reactTest"));
});
interface IServerTimeProps {
}
interface IServerTimeState {
time: string;
}
interface IServerTimeInputs {
userFormat?: HTMLInputElement;
}
class ServerTime extends React.Component<IServerTimeProps, IServerTimeState> {
inputs: IServerTimeInputs = {};
constructor() {
super();
this.state = { time: "unknown" }
}
render() {
return (
<div>
<div>Server time: { this.state.time }</div>
<input type="text" ref={ a => this.inputs.userFormat = a } defaultValue="s" ></input>
<button onClick={ this._buttonClick.bind(this) }>GetTime</button>
</div>
);
}
// Update state with value from server
_buttonClick(): void {
alert(`Format:${this.inputs.userFormat.value}`);
// This part requires a listening web server to work, but alert shows the user input
jQuery.ajax({
method: "POST",
data: { format: this.inputs.userFormat.value },
url: "/Home/ServerTime",
success: (result) => {
this.setState({ time : result });
}
});
}
}
