[react] 动态JSX标签

• 原本的写法

const input = this.props.long ? <textarea
  onChange={this.props.onChange}
  className="make-this-pretty"
  id="important-input"
  name="important-input"
/> : <input
  onChange={this.props.onChange} 
  className="make-this-pretty"
  id="important-input"
  name="important-input"
/>;

• 改进的写法

const Tag = this.props.long ? "textarea" : "input";

const input = <Tag 
                  onChange={this.props.onChange}
                  className="make-this-pretty"
                  id="important-input"
              />;