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);