Javascript String检查字母个数

1 <script>
2 var txt="ABCDEFGHIJKLMNOPQRSTUVWXYZvshjkdjlksdhbasndhbawnieoqawinsbdvhzohcvikzbncxiouj";
3 var index=0,count=0,position=0;
4 index = txt.indexOf("h",position);
5 document.getElementById("demo").innerHTML=index;
6 while(index!=-1){
7         count++;
8            position = index + 1;
9         index = txt.indexOf("h",position);
10 }
11 document.getElementById("demo").innerHTML=count;
12 </script>

摘自https://www.cnblogs.com/ghostang/