问在html5画布游戏中添加计时器

EN

var startTime = new Date().getTime();  // set this at the game start!
var time   = 0;
var collided  = false;
var engine;

function collision(){
  collided = true;  // if element is overlapping set to true
  time = parseInt((new Date().getTime()-startTime)/1000, 10);
}

function game(){  
  if(collided){
    alert("GAME OVER "+ time); 
    return clearInterval( engine ); 
  }
  /* GAME LOGIC HERE */
}

engine = setInterval(game ,25);


$('button').click(collision); // just to simulate