Typescript输入onchange event.target.value

在我的react和typescript应用程序中，我使用:

onChange={(e) => data.motto = (e.target as any).value}

我如何正确地定义类的类型，这样我就不必用任何类型系统来破解我的方法?

export interface InputProps extends React.HTMLProps<Input> {
...

}

export class Input extends React.Component<InputProps, {}> {
}

如果我放target: {value: string};我得到:

ERROR in [default] /react-onsenui.d.ts:87:18
Interface 'InputProps' incorrectly extends interface 'HTMLProps<Input>'.
  Types of property 'target' are incompatible.
    Type '{ value: string; }' is not assignable to type 'string'.

当前回答

这是当你使用FileList对象的时候:

onChange={(event: React.ChangeEvent<HTMLInputElement>): void => {
  const fileListObj: FileList | null = event.target.files;
  if (Object.keys(fileListObj as Object).length > 3) {
    alert('Only three images pleaseeeee :)');
  } else {
    // Do something
  }

  return;
}}

2019-09-27 10:17:49

其他回答

在TypeScript中使用的正确方法是

  handleChange(e: React.ChangeEvent<HTMLInputElement>) {
    // No longer need to cast to any - hooray for react!
    this.setState({temperature: e.target.value});
  }

  render() {
        ...
        <input value={temperature} onChange={this.handleChange} />
        ...
    );
  }

遵循完整的类，更好地理解:

import * as React from "react";

const scaleNames = {
  c: 'Celsius',
  f: 'Fahrenheit'
};


interface TemperatureState {
   temperature: string;
}

interface TemperatureProps {
   scale: string;

}

class TemperatureInput extends React.Component<TemperatureProps, TemperatureState> {
  constructor(props: TemperatureProps) {
    super(props);
    this.handleChange = this.handleChange.bind(this);
    this.state = {temperature: ''};
  }

  //  handleChange(e: { target: { value: string; }; }) {
  //    this.setState({temperature: e.target.value});  
  //  }


  handleChange(e: React.ChangeEvent<HTMLInputElement>) {
    // No longer need to cast to any - hooray for react!
    this.setState({temperature: e.target.value});
  }

  render() {
    const temperature = this.state.temperature;
    const scale = this.props.scale;
    return (
      <fieldset>
        <legend>Enter temperature in {scaleNames[scale]}:</legend>
        <input value={temperature} onChange={this.handleChange} />
      </fieldset>
    );
  }
}

export default TemperatureInput;

2018-04-13 15:08:06

您可以执行以下操作:

import { ChangeEvent } from 'react';

const onChange = (e: ChangeEvent<HTMLInputElement>)=> {
   const newValue = e.target.value;
}

2018-02-09 06:44:43

这是当你使用FileList对象的时候:

onChange={(event: React.ChangeEvent<HTMLInputElement>): void => {
  const fileListObj: FileList | null = event.target.files;
  if (Object.keys(fileListObj as Object).length > 3) {
    alert('Only three images pleaseeeee :)');
  } else {
    // Do something
  }

  return;
}}

2019-09-27 10:17:49

将字符串转换为数字简单答案

<input
    type="text"
    value={incrementAmount}
    onChange={(e) => {
      setIncrementAmmount(+e.target.value);
    }}
/>

2022-09-20 16:41:06

const handleChange = (
    e: ChangeEvent<HTMLInputElement>
  ) => {
    const { name, value } = e.target;
    this.setState({ ...currentState, [name]: value });
  };

您可以将此应用于表单组件中的每个输入元素

2022-11-24 19:04:30

Typescript输入onchange event.target.value

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