var url = window.location.href;
window.location = url.replace('#', url.indexOf('?') ? '&' : '?');
https://oauth.vk.com/authorize?client_id=*&display=page&redirect_uri=https://api.vk.com/blank.html&scope=offline,wall,photos&response_type=token&v=5.101&state=*
https://api.vk.com/blank.html#access_token=*&expires_in=0&user_id=*&state=*
filter_input(INPUT_POST, 'foo')
<input type="image" src="...">
<button><img src="..."></button>