this.js

render: function() {
   return <div className="register-form">
     {this.renderForm()}
   </div>
 },
 renderForm: function() {
   return <form onSubmit={this.formSubmit}>
     <div className="form-group">
       <label for="register-email">Email</label>
       <input
         type="text"
         className="form-control"
         id="register-email"
         placeholder="Email"
         value={this.state.email}
         onChange={this.handleEmailChange}
         />
     </div>
     <div className="form-group">
       <label for="register-password">Password</label>
       <input
         type="password"
         className="form-control"
         id="register-password"
         placeholder="Password"
         value={this.state.password}
         onChange={this.handlePasswordChange}
         />
     </div>
     <button onClick={this.formSubmit} className="btn btn-success btn-block">{this.props.button}</button>
   </form>
 },