"file.length" is not accuracy

[YaoyongYu]

var saveFile = new File(et_outpath.text + "/" + (m + 1) + "_" + (n + 1) + houzui);
                do {
                qlty = qlty-5;
                saveFile=new File(exportWeb (saveFile,qlty,format,png8))
                saveFile.remove();
                exportWeb (saveFile, qlty, format,png8);
                     if (qlty<=0){ 
                         alert("无法压缩至指定文件大小"); 
                            app.activeDocument.close(SaveOptions.DONOTSAVECHANGES);
                            ac_doc.selection.deselect();
                            w.enabled = true;
                            bt_cut.text = "开始";
                            return;
                        }
                } while (saveFile.length > parseInt(et_imgkb.text)*1024)
         app.activeDocument.close(SaveOptions.DONOTSAVECHANGES);

[tssee]

You could enter the full script

and thus more clearly the problem.