Вызов функции по кнопке [требует правки]

function myFunction() { 
//берём элемент с id = demo и записываем в него дату и время 
    document.getElementById('demo').innerHTML=Date(); 
}

<button onclick="myFunction()">Получить дату</button> 
<p id="demo"></p>

alert ("You win") 
function rand (min, max){ 
   var rand = min + Math.floor(Math.random() * (max + 1 - min)); 
   if (rand == 2){ 
      alert('You win!');} 
else{  
      alert ('you lose!');} 
}

<button id="thu" OnClick="rand (1,2)">GAME</button>

alert ("You win"); 
function rand (min, max){ 
   var rand = min + Math.floor(Math.random() * (max + 1 - min)); 
   if (rand == 2){ 
      alert('You win!');} 
else {  
      alert ('you lose!');} 
} 
 
document.getElementById("thu").addEventListener("click", function(){rand(1,2)}, false);

<button id="thu">GAME</button>

alert ("You win"); 
function rand (min, max){ 
   var rand = min + Math.floor(Math.random() * (max + 1 - min)); 
   if (rand == 2){ 
      alert('You win!');} 
else {  
      alert ('you lose!');} 
} 
 
document.getElementById("thu").onclick = function(){ 
   rand(1,2); 
};

<button id="thu">GAME</button>

alert ("You win"); 
function rand (min, max){ 
   var rand = min + Math.floor(Math.random() * (max + 1 - min)); 
   if (rand == 2){ 
      alert('You win!');} 
else {  
      alert ('you lose!');} 
} 
 
$("#thu").click(function(){ 
  rand(1,2); 
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script> 
<button id="thu">GAME</button>