new.tsx

import * as React from "react";
import * as ReactDOM from 'react-dom'

import { DefaultButton, PrimaryButton, Stack, IStackTokens } from '@fluentui/react';

export interface IButtonExampleProps {
    // These are set based on the toggles shown above the examples (not needed in real code)
    disabled?: boolean;
    checked?: boolean;
}

// Example formatting
const stackTokens: IStackTokens = { childrenGap: 40 };

export const ButtonDefaultExample: React.FunctionComponent<IButtonExampleProps> = props => {
    const { disabled, checked } = props;

    return (
        <Stack horizontal tokens={stackTokens}>
            <DefaultButton text="Standard" onClick={_alertClicked} allowDisabledFocus disabled={disabled} checked={checked} />
            <PrimaryButton text="Primary" onClick={_alertClicked} allowDisabledFocus disabled={disabled} checked={checked} />
        </Stack>
    );
};

function _alertClicked(): void {
    alert('Clicked');
}

ReactDOM.render(<ButtonDefaultExample />, document.getElementById('main'))