React form with the event

This section will discuss how to use the forms in React.

It is an example of a simple

In the example we set the value of the input box inputvalue = {this.state.data}.When the input box value changes we can update the state. We can use theonChange event to listen for changes in input and modify the state.

var HelloMessage = React.createClass({
  getInitialState: function() {
    return {value: 'Hello w3big!'};
  },
  handleChange: function(event) {
    this.setState({value: event.target.value});
  },
  render: function() {
    var value = this.state.value;
    return <div>
            <input type="text" value={value} onChange={this.handleChange} /> 
            <h4>{value}</h4>
           </div>;
  }
});
ReactDOM.render(
  <HelloMessage />,
  document.getElementById('example')
);

try it"

The above code will render a value of Hello w3big! Input element, and updated in response to user input values ​​onChange event.

Example 2

In the following example I will show you how to use it in the form on the subassembly.onChange method triggers an update and update state value is transmitted to the input box sub-assembly of the valueup re-rendering interface.

You need your parent component is transmitted to the sub-assembly by creating an event handler(handleChange), and as a prop(updateStateProp).

var Content = React.createClass({
  render: function() {
    return  <div>
            <input type="text" value={this.props.myDataProp} onChange={this.props.updateStateProp} /> 
            <h4>{this.props.myDataProp}</h4>
            </div>;
  }
});
var HelloMessage = React.createClass({
  getInitialState: function() {
    return {value: 'Hello w3big!'};
  },
  handleChange: function(event) {
    this.setState({value: event.target.value});
  },
  render: function() {
    var value = this.state.value;
    return <div>
            <Content myDataProp = {value} 
              updateStateProp = {this.handleChange}></Content>
           </div>;
  }
});
ReactDOM.render(
  <HelloMessage />,
  document.getElementById('example')
);

try it"

React event

The following examples demonstrate to modify the data through the onClick event:

var HelloMessage = React.createClass({
  getInitialState: function() {
    return {value: 'Hello w3big!'};
  },
  handleChange: function(event) {
    this.setState({value: '本教程'})
  },
  render: function() {
    var value = this.state.value;
    return <div>
            <button onClick={this.handleChange}>点我</button>
            <h4>{value}</h4>
           </div>;
  }
});
ReactDOM.render(
  <HelloMessage />,
  document.getElementById('example')
);

try it"

When you need to update thestate from the parent component sub-assembly, you need to parent component by creating an event handler (handleChange),and delivered to your subassembly asprop(updateStateProp). Examples are as follows:

var Content = React.createClass({
  render: function() {
    return  <div>
              <button onClick = {this.props.updateStateProp}>点我</button>
              <h4>{this.props.myDataProp}</h4>
           </div>
  }
});
var HelloMessage = React.createClass({
  getInitialState: function() {
    return {value: 'Hello w3big!'};
  },
  handleChange: function(event) {
    this.setState({value: '本教程'})
  },
  render: function() {
    var value = this.state.value;
    return <div>
            <Content myDataProp = {value} 
              updateStateProp = {this.handleChange}></Content>
           </div>;
  }
});
ReactDOM.render(
  <HelloMessage />,
  document.getElementById('example')
);

try it"