// Concentration Memory Game with Images - Head Script
// copyright Stephen Chapman, 28th February 2006
// you may copy this script provided that you retain the copyright notice

var back = 'back.png';
var tile = ['img0.png','img1.png','img2.png','img3.png','img4.png','img5.png','img6.png','img7.png','img8.png','img9.png','img10.png','img11.png','img12.png','img13.png','img14.png'];

function randOrd(a, b){
     return (Math.round(Math.random())-0.5);
     } 

var im = []; 
for (var i = 0; i < 15; i++) {
     im[i] = new Image();
     im[i].src = tile[i]; 
     tile[i] = '<img src="'+tile[i]+'" height="60" width="60" \/>'; 
     tile[i+15] = tile[i];
     } 
function displayBack(i) {
     document.getElementById('t'+i).innerHTML = '<div onclick="disp('+i+');return false;"><img src="'+back+'" height="60" width="60" \/><\/div>';
     } 
var ch1, ch2, tmr, tno, tid, cid, cnt; 
window.onload=starter; 
function starter() {
     for (var i = 0; i <= 29 ;i++) displayBack(i);
     clearInterval(tid);
     tmr = tno = cnt = 0;
     tile.sort( randOrd );
     cntr(); 
     tid = setInterval('cntr()', 1000);
     } 
function cntr() {
     var min = Math.floor(tmr/60);
     var sec = tmr%60;
     mem.cnt.value = min+':'+ (sec<10 ? '0' : '') + sec;tmr++;
     } 
function disp(sel) {
     if (tno>1) {
          clearTimeout(cid); 
          conceal();
          }
     document.getElementById('t'+sel).innerHTML = tile[sel];
     if (tno==0) ch1 = sel;
     else {
          ch2 = sel;  
          cid = setTimeout('conceal()', 900);
          }
     tno++;
     } 
function conceal() {
     tno = 0; 
     if (tile[ch1] != tile[ch2]) {
          displayBack(ch1);
          displayBack(ch2);
          } 
     else cnt++; 
     if (cnt >= 15) clearInterval(tid);
     }