js之用IndexOf返回指定字符串的次数

代码

  var Str = "strs,strs,stras,str,strs,strs";
    var subStr ="strs" ;

    var count = 0; 
    var offset = 0;
     do { offset = Str.indexOf(subStr, offset);
    if(offset != -1)
     { count++; offset += subStr.length;
      } }while(offset != -1);
    alert(count);