login.js

import React from 'react';
export default class Login extends React.Component{
    constructor() {
        super()
        this.state = {
         username: '',
         password: '',
         isLogined: false
        }
    }
    handleInputChange = (event) => {
        this.setState({
         [event.target.name]: event.target.value
        })
       }
   submitClick=() =>
    {
            if((this.state.username=="krishankantsinghal") && (this.state.password=="krishankant123"))
            {
                this.setState({isLogined:true});
            }
    }
    render()
    {
        return (
        <div>
          <input type="text" name="username" hint="username" onChange={this.handleInputChange} />
          <input type="password" name="password" hint="password" onChange={this.handleInputChange} />
          <button  name="submit" onClick={this.submitClick}> Submit</button>
         </div>
        );
    }
}