[英]Why is React telling me that this.handleClick is not a function?
我正在使用 React 创建一个简单的计算器,我正在尝试将 onClick function 添加到按钮。 我正在使用与 tictactoe 游戏的反应教程中使用的相同技术,但是当我单击任何按钮时,我只会收到以下错误消息:
Uncaught TypeError: this.handleClick is not a function
at onClick (index.js:71)
at HTMLUnknownElement.callCallback (react-dom.development.js:188)
at Object.invokeGuardedCallbackDev (react-dom.development.js:237)
at invokeGuardedCallback (react-dom.development.js:292)
at invokeGuardedCallbackAndCatchFirstError (react-dom.development.js:306)
at executeDispatch (react-dom.development.js:389)
at executeDispatchesInOrder (react-dom.development.js:414)
at executeDispatchesAndRelease (react-dom.development.js:3278)
at executeDispatchesAndReleaseTopLevel (react-dom.development.js:3287)
at forEachAccumulated (react-dom.development.js:3259)
at runEventsInBatch (react-dom.development.js:3304)
at runExtractedPluginEventsInBatch (react-dom.development.js:3514)
at handleTopLevel (react-dom.development.js:3558)
at batchedEventUpdates$1 (react-dom.development.js:21871)
at batchedEventUpdates (react-dom.development.js:795)
at dispatchEventForLegacyPluginEventSystem (react-dom.development.js:3568)
at attemptToDispatchEvent (react-dom.development.js:4267)
at dispatchEvent (react-dom.development.js:4189)
at unstable_runWithPriority (scheduler.development.js:653)
at runWithPriority$1 (react-dom.development.js:11039)
at discreteUpdates$1 (react-dom.development.js:21887)
at discreteUpdates (react-dom.development.js:806)
at dispatchDiscreteEvent (react-dom.development.js:4168)
我的代码如下:
import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
class Screen extends React.Component {
render() {
return (
<p>99+10</p>
);
}
}
class Operators extends React.Component {
render() {
return (
<div>
{this.props.renderButton('+')}
{this.props.renderButton('-')}
{this.props.renderButton('x')}
{this.props.renderButton('/')}
</div>
);
}
}
class Numbers extends React.Component {
render() {
return (
<div>
<div className="nums-row">
{this.props.renderButton(1)}
{this.props.renderButton(2)}
{this.props.renderButton(3)}
</div>
<div className="nums-row">
{this.props.renderButton(4)}
{this.props.renderButton(5)}
{this.props.renderButton(6)}
</div>
<div className="nums-row">
{this.props.renderButton(7)}
{this.props.renderButton(8)}
{this.props.renderButton(9)}
</div>
<div className="nums-row">
{this.props.renderButton('.')}
{this.props.renderButton(0)}
{this.props.renderButton('=')}
</div>
</div>
);
}
}
function CalculatorButton(props) {
return (
<button onClick={props.onClick} >
{props.text}
</button>
);
}
class Calculator extends React.Component {
handleClick(text) {
console.log(text);
}
renderButton(text) {
return (
<CalculatorButton
onClick= {() => this.handleClick(text)}
text={text}
/>
);
}
render() {
return (
<div className="calculator-container">
<div className="calculator">
<div className="screen">
<Screen />
</div>
<div className="buttons">
<div className="numbers">
<Numbers renderButton={this.renderButton} />
</div>
<div className="operators">
<Operators renderButton={this.renderButton} />
</div>
</div>
</div>
</div>
);
}
}
ReactDOM.render(
<Calculator />,
document.getElementById('root')
);
这是界面的图片,这样可能更容易理解我在问题开始时所说的内容。
提前感谢您的帮助。
您需要将renderButton
function 绑定到Calculator
组件实例。
这可以通过多种方式完成:
#1。 在构造函数中:
class Calculator extends React.Component {
constructor(props) {
super(props);
this.renderButton = this.renderButton.bind(this);
}
/* ... */
}
#2。 在渲染中:
<Numbers renderButton={this.renderButton.bind(this)} />
#3。 或者通过将renderButton
方法更改为箭头 function:
renderButton = (text) => {
/* ... */
}
更多细节以及一些优点和缺点可以在React 常见问题解答部分找到。
this.props.renderButton('+')
立即调用renderButton
并将返回值分配为事件处理程序。
<button onClick={(e) => this.deleteRow(id, e)}>Delete Row</button> <button onClick={this.deleteRow.bind(this, id)}>Delete Row</button>
上面两行是等价的,分别使用箭头函数和Function.prototype.bind。
在这两种情况下,表示 React 事件的 e 参数将作为 ID 之后的第二个参数传递。 使用箭头 function,我们必须显式传递它,但绑定任何进一步的 arguments 都会自动转发。
要解决您的问题,只需使用 Arrow function。 为此,请将两个事件处理程序handleClick 和 renderButton替换为以下代码。 它完美地工作。
handleClick = (text) => {
console.log(text);
};
renderButton = (text) => {
return (
<CalculatorButton
onClick={() => this.handleClick(text)}
text={text}
/>
);
};
您还可以将 onclick 设置为 null,认为 <ComboSelect... onClick={null} /> 对我来说是正确的
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.