Why isn't my input value updating with React?

You need to perform a couple of steps:

1. Your input needs to only use the value and onChange props, do not use defaultValue
2. Initialize your state using your props to set your default value
3. Update your state when your props change

So, for example:

const MyComponent = React.createClass({

  propTypes: {
    defaultInputValue: React.PropTypes.string
  },

  getInitialState() {
    return {
      inputValue: this.props.defaultInputValue
    };
  },

  componentWillReceiveProps(nextProps) {
    if (nextProps.defaultInputValue !== this.props.inputValue) {
      //Forcibly overwrite input value to new default if the default ever changes
      this.setState({inputValue: nextProps.defaultInputValue});
    }
  },

  render() {
    return <input type="text"
                  value={this.state.inputValue}
                  onChange={e => this.setState({inputValue: e.target.value})} />;
  }
});

In general initializing state off of props is a no-no. I would probably cringe a little bit if I saw this come across in a code review as there is probably some behavior that can be simplified.

You can also do:

<input value={this.state.inputValue || this.props.defaultInputValue} />

Such that the value of the input reverts to the prop value if you ever clear out the input. In this case you wouldn't have to forcibly overwrite the state with the new props.

AoA
We can do it as this.We Must have to use onChnage() Event.

<input placeholder="as_you_want"
       value={this.state.as_your_state}
       onChange={e => {
           this.setState({ as_your_state: e.target.value });
           this.value = this.state.as_your_state;
       }}
/>

Hope This Works.