<script type="text/javascript">

  var scoreStr = "小明:87;小花:81;小红:97;小天:76;小张:74;小小:94;小西:90;小伍:76;小迪:64;小曼:76";
 
  //从数组中将成绩撮出来，然后求和取整，并输出。
  var myarr = scoreStr.split(';');
  var sum = 0;
  var averagesum = 0;
  for(var i = 0; i<= myarr.length;i++){
     sum += parseInt(myarr[i].substr(myarr[i].indexOf(':') + 1));
  }
  averagesum = sum / myarr.length;
  document.write(parseInt(averagesum));
</script>