import React, { useState } from 'react'


const [rememberUser, setRememberUser] = useState(true) //use false for unchecked initially


<input
   type="checkbox"
   checked={rememberUser}
   onChange={() => {
      setRememberUser(!rememberUser)
   }}
/>

Don't make it too hard. First, understand a simple example given below. It will be clear to you. In this case, just after pressing the checkbox, we will grab the value from the state(initially it's false), change it to other value(initially it's true) & set the state accordingly. If the checkbox is pressed for the second time, it will do the same process again. Grabbing the value (now it's true), change it(to false) & then set the state accordingly(now it's false again. The code is shared below.

第1部分

state = {
  verified: false
} // The verified state is now false

第2部分

verifiedChange = e => {
  // e.preventDefault(); It's not needed
  const { verified } = e.target;
  this.setState({
    verified: !this.state.verified // It will make the default state value(false) at Part 1 to true 
  });
}; 

第3部分

  <form> 
      <input
          type="checkbox"
          name="verified"
          id="verified"
          onChange={this.verifiedChange} // Triggers the function in the Part 2
          value={this.state.verified}
      />
      <label for="verified">
      <small>Verified</small>
      </label>
  </form>

要与复选框交互，您需要在更改复选框后更新复选框的状态。你可以使用defaultChecked来设置默认值。

一个例子:

<input type="checkbox" defaultChecked={this.state.chkbox} onChange={this.handleChangeChk} />

有几种方法可以做到这一点，以下是几种:

使用State Hooks编写:

function Checkbox() {
  const [checked, setChecked] = React.useState(true);

  return (
    <label>
      <input type="checkbox"
        defaultChecked={checked}
        onChange={() => setChecked(!checked)}
      />
      Check Me!
    </label>
  );
}

ReactDOM.render(
  <Checkbox />,
  document.getElementById('checkbox'),
);

下面是JSBin上的一个现场演示。

使用组件编写:

class Checkbox extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      isChecked: true,
    };
  }
  toggleChange = () => {
    this.setState({
      isChecked: !this.state.isChecked,
    });
  }
  render() {
    return (
      <label>
        <input type="checkbox"
          defaultChecked={this.state.isChecked}
          onChange={this.toggleChange}
        />
        Check Me!
      </label>
    );
  }
}

ReactDOM.render(
  <Checkbox />,
  document.getElementById('checkbox'),
);

下面是JSBin上的一个现场演示。

它的工作

<input type="checkbox" value={props.key} defaultChecked={props.checked} ref={props.key} onChange={this.checkboxHandler} />

函数初始化它

{this.viewCheckbox({ key: 'yourKey', text: 'yourText', checked: this.state.yourKey })}

您可以将"true"或""传递给input复选框的checked属性。空引号("")将被理解为假的，该项将不被选中。

let checked = variable === value ? "true" : "";
<input
     className="form-check-input"
    type="checkbox"
    value={variable}
    id={variable}
    name={variable}
    checked={checked}
/>
<label className="form-check-label">{variable}</label>