javascript根据文件字节数返回文件大小

 function getFileSize(fileByte) {
       var fileSizeByte = fileByte;
       var fileSizeMsg = "";
       if(fileSizeByte < 1024){
           fileSizeMsg = fileSizeByte  + "B";
       }else if (fileSizeByte < 1048576) {
           fileSizeMsg = window.parseFloat(((fileSizeByte / 1024)).toFixed(2)) + "KB";
       }else if (fileSizeByte == 1048576) {
           fileSizeMsg = "1MB";
       }else if (fileSizeByte > 1048576 && fileSizeByte < 1073741824){
           fileSizeMsg = window.parseFloat(((fileSizeByte / (1024 * 1024))).toFixed(2)) + "MB";
       }else if (fileSizeByte > 1048576 && fileSizeByte == 1073741824){
           fileSizeMsg = "1GB";
       }else if (fileSizeByte > 1073741824 && fileSizeByte < 1099511627776){
           fileSizeMsg = window.parseFloat(((fileSizeByte / (1024 * 1024 * 1024))).toFixed(2)) + "GB";
       }else{
           fileSizeMsg = "文件超过1TB";
       }
       return fileSizeMsg;
     }

会根据字节数进行转换成文件大小，如果转换后有小数点则保留两位小数，并且小数点后只有一位或没有小数点时去除最后无用的0.