为什么我的javascript代码没有运行？ 画布和javascript事件

Question

My javascript code is not running, but the html drawing the canvas is..... Im trying to add an event listener on a canvas html element. Each time i click the element its supposed to give me an alert. Ive tried this on firefox and google chrome.

<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

convert

}   
    });
}, false);

to

    });
}, false);