public function registerUser(Request $request)
{
    $rules = [
        'username' => 'required',
        'email' => 'required|email',
        'password' => 'required|min:5'
    ];

    $validator = Validator::make($request->all(), $rules);

    if ($validator->fails()) {
        return response()->json(['errors' => $validator->messages()]);
    }

    $user = User::create(request(['username', 'email', 'password']));

    return response()->json('success');
}

constructor(props){
        super(props);
        this.state={
            userName:'',
            userEmail:'',
            userPassword:'',
            errors:[]
        }
    }

    axios({
        method: 'post',
        url: API_URL+'signup',
        data: {
            username: userName,
            email: userEmail,
            password: userPassword
        }
    })
    .then(function (response) {
        var count = Object.keys(response.data.errors).length;
        if (count > 0) {
            console.log(response.data.errors);
            var newState = new Array();
            newState.push(response.data.errors);
            this.setState({
                errors: newState
            })
        }
    })
    .catch(function (error) {
        console.log(error);
    });