我在渲染函数中有一个简单的表单,如下所示:
render : function() {
return (
<form>
<input type="text" name="email" placeholder="Email" />
<input type="password" name="password" placeholder="Password" />
<button type="button" onClick={this.handleLogin}>Login</button>
</form>
);
},
handleLogin: function() {
//How to access email and password here ?
}
我应该在我的handleLogin: function(){…}访问电子邮件和密码字段?
在javascript的许多事件中,我们有event,它给出一个对象,包括发生了什么事件,值是什么等等。
这也是我们在ReactJs中使用的表单…
所以在你的代码中,你将状态设置为新值…就像这样:
class UserInfo extends React.Component {
constructor(props) {
super(props);
this.handleLogin = this.handleLogin.bind(this);
}
handleLogin(e) {
e.preventDefault();
for (const field in this.refs) {
this.setState({this.refs[field]: this.refs[field].value});
}
}
render() {
return (
<div>
<form onSubmit={this.handleLogin}>
<input ref="email" type="text" name="email" placeholder="Email" />
<input ref="password" type="password" name="password" placeholder="Password" />
<button type="button">Login</button>
</form>
</div>
);
}
}
export default UserInfo;
另外,这是React v.16中的表单示例,只是作为将来创建表单的参考:
class NameForm extends React.Component {
constructor(props) {
super(props);
this.state = {value: ''};
this.handleChange = this.handleChange.bind(this);
this.handleSubmit = this.handleSubmit.bind(this);
}
handleChange(event) {
this.setState({value: event.target.value});
}
handleSubmit(event) {
alert('A name was submitted: ' + this.state.value);
event.preventDefault();
}
render() {
return (
<form onSubmit={this.handleSubmit}>
<label>
Name:
<input type="text" value={this.state.value} onChange={this.handleChange} />
</label>
<input type="submit" value="Submit" />
</form>
);
}
}
如果元素名多次出现,则必须使用forEach()。
html
<input type="checkbox" name="delete" id="flizzit" />
<input type="checkbox" name="delete" id="floo" />
<input type="checkbox" name="delete" id="flum" />
<input type="submit" value="Save" onClick={evt => saveAction(evt)}></input>
js
const submitAction = (evt) => {
evt.preventDefault();
const dels = evt.target.parentElement.delete;
const deleted = [];
dels.forEach((d) => { if (d.checked) deleted.push(d.id); });
window.alert(deleted.length);
};
注意,本例中的dels是RadioNodeList,而不是数组,也不是Iterable。forEach()是列表类的内置方法。这里不能使用map()或reduce()。
同样,这个也可以用。
handleChange: function(state,e) {
this.setState({[state]: e.target.value});
},
render : function() {
return (
<form>
<input type="text" name="email" placeholder="Email" value={this.state.email} onChange={this.handleChange.bind(this, 'email')} />
<input type="password" name="password" placeholder="Password" value={this.state.password} onChange={this.handleChange.bind(this, 'password')}/>
<button type="button" onClick={this.handleLogin}>Login</button>
</form>
);
},
handleLogin: function() {
console.log("EMail: ", this.state.email);
console.log("Password: ", this.state.password);
}
使用输入中的change事件来更新组件的状态,并在handllogin中访问它:
handleEmailChange: function(e) {
this.setState({email: e.target.value});
},
handlePasswordChange: function(e) {
this.setState({password: e.target.value});
},
render : function() {
return (
<form>
<input type="text" name="email" placeholder="Email" value={this.state.email} onChange={this.handleEmailChange} />
<input type="password" name="password" placeholder="Password" value={this.state.password} onChange={this.handlePasswordChange}/>
<button type="button" onClick={this.handleLogin}>Login</button>
</form>);
},
handleLogin: function() {
console.log("EMail: " + this.state.email);
console.log("Password: " + this.state.password);
}
工作小提琴。
此外,阅读文档,有一个完整的部分专门用于表单处理:表单
以前你也可以使用React的双向数据绑定助手mixin来实现同样的事情,但现在它被弃用了,取而代之的是设置值和更改处理程序(如上所述):
var ExampleForm = React.createClass({
mixins: [React.addons.LinkedStateMixin],
getInitialState: function() {
return {email: '', password: ''};
},
handleLogin: function() {
console.log("EMail: " + this.state.email);
console.log("Password: " + this.state.password);
},
render: function() {
return (
<form>
<input type="text" valueLink={this.linkState('email')} />
<input type="password" valueLink={this.linkState('password')} />
<button type="button" onClick={this.handleLogin}>Login</button>
</form>
);
}
});
文档在这里:双向绑定助手。
对于那些不想使用ref和OnChange事件重置状态的人,你可以只使用简单的OnSubmit句柄和循环FormData对象。
注意,你不能直接访问formData.entries(),因为它是一个可迭代对象,你必须循环遍历它。
这个例子使用了React Hooks:
const LoginPage = () => {
const handleSubmit = (event) => {
const formData = new FormData(event.currentTarget);
event.preventDefault();
for (let [key, value] of formData.entries()) {
console.log(key, value);
}
};
return (
<div>
<form onSubmit={handleSubmit}>
<input type="text" name="username" placeholder="Email" />
<input type="password" name="password" placeholder="Password" />
<button type="submit">Login</button>
</form>
</div>
);
};
如果你使用的是TypeScript:
export const LoginPage: React.FC<{}> = () => {
const handleSubmit: React.FormEventHandler<HTMLFormElement> = (event) => {
const formData = new FormData(event.currentTarget);
event.preventDefault();
for (let [key, value] of formData.entries()) {
console.log(key, value);
}
};
return (
<div>
<form onSubmit={handleSubmit}>
<input type="text" name="username" placeholder="Email" />
<input type="password" name="password" placeholder="Password" />
<button type="submit">Login</button>
</form>
</div>
);
};