generals.js

function startTimer(duration, display) {
    var timer = duration, minutes, seconds;
    setInterval(function () {
        minutes = parseInt(timer / 60, 10);
        seconds = parseInt(timer % 60, 10);

        minutes = minutes < 10 ? "0" + minutes : minutes;
        seconds = seconds < 10 ? "0" + seconds : seconds;
        display.textContent = minutes + ":" + seconds;

        if (--timer < 0) {
            timer = duration;
        }
    }, 1000);
};

function checkForGame(p) {
	var time = 25;
	
	var gameChecker = setInterval(function() {
  	var gamePage = document.getElementById('game-page');
    console.log("Looking for game..");
    if (gamePage) {
    	startTimer(time, p);
      clearInterval(gameChecker);
    }
  }, 500);
};

var p = document.createElement("p");
p.style.color = 'white';
p.style.fontSize = '30px';
p.style.padding = '10px';
p.style.position = 'absolute';
p.style.backgroundColor = 'black';
p.style.marginTop = '100px';
p.style.zIndex = '9999';
p.innerHTML = "Waiting...";
document.body.insertBefore(p, document.body.firstChild);

console.log("Loaded...");
checkForGame(p);