js中字节B转化成KB，MB，GB

 function change(limit){
     var size = "";
     if(limit < 0.1 * 1024){                            //小于0.1KB，则转化成B
         size = limit.toFixed(2) + "B"
     }else if(limit < 0.1 * 1024 * 1024){            //小于0.1MB，则转化成KB
         size = (limit/1024).toFixed(2) + "KB"
     }else if(limit < 0.1 * 1024 * 1024 * 1024){        //小于0.1GB，则转化成MB
         size = (limit/(1024 * 1024)).toFixed(2) + "MB"
     }else{                                            //其他转化成GB
         size = (limit/(1024 * 1024 * 1024)).toFixed(2) + "GB"
     }

     var sizeStr = size + "";                        //转成字符串
     var index = sizeStr.indexOf(".");                    //获取小数点处的索引
     var dou = sizeStr.substr(index + 1 ,2)            //获取小数点后两位的值
     if(dou == "00"){                                //判断后两位是否为00，如果是则删除00
         return sizeStr.substring(0, index) + sizeStr.substr(index + 3, 2)
     }
     return size;
 }

 var newLimit = change(1048576);
 console.log(newLimit);