面向对象练习题

第一个

window.onload = function(){
    var Game = function(canvas , options){
        var _options = options || { width : 300 , height : 300 }
        var _pos = {x : _options.width / 2 , y : _options.height}
        canvas.onmousemove = function(e){
            _pos = {
                x : e.clientX / 2 ,
                y : e.clientY / 2
            };
            init();
        }
        function init(){
            canvas.style.width = _options.width + 'px';
            canvas.style.height = _options.height + 'px';
            canvas.style.left = _pos.x + 'px';
            canvas.style.top = _pos.y + 'px';
        }
        init();
        this.conTent("不在本方法内，调用一下");
    }
    Game.prototype.conTent = function(msg){
        console.log(msg);
    }
    var canvas = document.getElementById('canvas');
    new Game(canvas);
}