我有麻烦更新复选框的状态后,它被分配的默认值checked=“checked”在React。
var rCheck = React.createElement('input',
{
type: 'checkbox',
checked: 'checked',
value: true
}, 'Check here');
在分配checked="checked"后,我无法通过单击取消选中/选中来交互复选框状态。
我有麻烦更新复选框的状态后,它被分配的默认值checked=“checked”在React。
var rCheck = React.createElement('input',
{
type: 'checkbox',
checked: 'checked',
value: true
}, 'Check here');
在分配checked="checked"后,我无法通过单击取消选中/选中来交互复选框状态。
当前回答
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>
其他回答
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} />
<div className="form-group">
<div className="checkbox">
<label><input type="checkbox" value="" onChange={this.handleInputChange.bind(this)} />Flagged</label>
<br />
<label><input type="checkbox" value="" />Un Flagged</label>
</div>
</div
handleInputChange(event){ console.log(“event”,event.target.checked) }
上面的句柄在选中或未选中时给你true或false的值
我尝试使用Class组件来实现这一点: 您可以查看相同的消息
…
class Checkbox extends React.Component{
constructor(props){
super(props)
this.state={
checked:true
}
this.handleCheck=this.handleCheck.bind(this)
}
handleCheck(){
this.setState({
checked:!this.state.checked
})
}
render(){
var msg=" "
if(this.state.checked){
msg="checked!"
}else{
msg="not checked!"
}
return(
<div>
<input type="checkbox"
onChange={this.handleCheck}
defaultChecked={this.state.checked}
/>
<p>this box is {msg}</p>
</div>
)
}
}
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。