为什么SUM最后结果是NaN?
<script>
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";
var score=scorestr.split(";");
var sum=0;
var indexs;
for(var i=0;i<score.length;i++){
indexs=score[i].indexOf(":");
var show=score[i].substr(indexs+1);
sum+=parseInt(show);
}
document.write(+"总成绩:"+ sum);
document.write(+"平均成绩为:"+ Math.ceil(sum/score.length));
</script>