利用HTML5 Canvas制作一个简单的打飞机游戏

            this.fire = false;   
            this.firePerFrame = 10;   
            this.fireLevel = 1;   
        }else if(name==="star"){   
            this.width = Math.random()*2;   
            this.speed = 1*this.width/2;   
            this.lightLength = 5;   
            this.cacheCanvas = document.createElement("canvas");   
            this.cacheCtx = this.cacheCanvas.getContext(‘2d’);   
            this.cacheCanvas.width = this.width+this.lightLength*2;   
            this.cacheCanvas.height = this.width+this.lightLength*2;   
            this.painter.cache(this);   
        }else if(name==="badPlan"){   
            this.badKind = 1;   
            this.speed = 2;   
            this.rotateAngle = Math.PI;   
        }else if(name==="missle"){   
            this.width = missleWidth;   
        }else if(name==="boom"){   
            this.width = boomWidth;   
        }else if(name==="food"){   
            this.width = 40;   
            this.speed = 3;   
            this.kind = "LevelUP"  
        }