爲什麼我的JavaScript代碼不能運行？ canvas和javascript事件

Question

我的javascript代碼沒有運行，但繪製畫布的html是..... 我試圖在畫布html元素上添加一個事件監聽器。每次我點擊它應該給我一個警報的元素。我曾嘗試過這在Firefox和谷歌瀏覽器。

<script language = "javascript" type = "text/javascript"> 

alert("yo"); 
canvas.addEventListener('click', function() {}, false); 



var elem = document.getElementById("checkersq"), 
elemLeft = elem.offsetLeft, 
elemTop = elem.offsetTop, 
context = elem.getContext('2d'), 
elements = []; 

elem.addEventListener('click', function(event){ 

    var x = event.pageX - elemLeft, 
     y = event.pageY - elemTop; 

    elements.forEach(function(element){ 

     if (y > element.top && y < element.top + element.height 
      && x > element.left && x < element.left + element.width){ 

        alert('clicked an element'); 

      } 

     } 
    }); 
}, false); 

elements.push({ 
    colour: '#05EFFF', 
    width: 150, 
    height: 200, 
    top: 20, 
    left: 15 
}); 

elements.forEach(function(element) { 

    context.fillStyle = element.colour; 
    context.fillRect(element.left, element.top, element.width, element.height); 
}); 

Answer 1

轉換

} 
    }); 
}, false); 

到

}); 
}, false);