用js实现读取出字符串中每个字符重复出现的次数？

<script>
			var str="dfjkfkhsdjk hksjh",
                i=0,
                obj={};
            for(i=0;i<str.length;i++) {
                var ch=str.charAt(i);                    
                if (!obj[ch]) {
                    obj[ch]=1;
                } else{
                    obj[ch]++;
                }    
            }
            for(var r in obj)
            {
                console.log(r+","+obj[r]);
            }
		</script>
<script>
			var str="dfjkfkhsdjk hksjh",