In ReactJS how to store data as JSON while Clicking Submit button?

Question

In ReactJS how to store data as JSON when clicking button, I don't have any experiance in React So please explain briefly Guys. In Forms when clicking Submit button i had to store data from the given path.

class EmpForms extends React.Component {

constructor(props) {
    super(props)
    this.state = {
        EmpNumber: 0,
        EmpName: '', 
    };
    this.handleEmpNum = this.handleEmpNum.bind(this);
    this.handleEmpName = this.handleEmpName.bind(this);
}
handleEmpNum(event) {
    this.setState({ EmpNumber: event.target.value });
}
handleEmpName(event) {
    this.setState({ EmpName: event.target.value });
}
FormSubmit(event) {
   // Codes..
    alert(this.state.EmpNumber + " Stored in Emp File ");

}
render() {
    return (
        <div>
            <form onSubmit={this.FormSubmit}>
                <h1>Employee Details</h1><br></br>
                <div>Employee Number <input type="Number" placeholder="EmpNo" value={this.state.EmpNumber} onChange={this.handleEmpNum}></input></div><br></br>
                <div>Employee Name <input type="text" placeholder="EmpName" value={this.state.EmpName} onChange={this.handleEmpName}></input></div><br></br>
               <input type="submit" />
            </form>

        </div>
    );
}

} ReactDOM.render(, document.getElementById('App'));