JavaScript String 检测字母出现个数

 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>