How do I to delete/trash/remove a csv file if exists - csv

Question

I'm trying to create an export to csv apps script but it will not delete existing csv files sitting in the same folder. I would like to either trash them or overwrite them.
Here's the code I've already tried
function saveAsCSV() {
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheets = ss.getSheets();
// create a folder from the name of the spreadsheet
// var folder = DriveApp.createFolder(ss.getName().toLowerCase().replace(/ /g,'_') + '_csv_' + new Date().getTime());
// var folder = DriveApp.createFolder(ss.getName().toLowerCase().replace(/ /g,'_') + '_csv_');
for (var i = 0 ; i < sheets.length ; i++) {
var sheet = sheets[i];
// append ".csv" extension to the sheet name
fileName = sheet.getName() + ".csv";
// convert all available sheet data to csv format
var csvFile = convertRangeToCsvFile_(fileName, sheet);
var file = DriveApp.getFileById(ss.getId());
var folder = file.getParents();
folder = folder.next();
// loop through files and delete ones with existing name
var existingfiles = folder.getFiles()
for (var j = 0 ; j<existingfiles.length;j++){
var existingfile = existingfiles[j].next()
if (existingfile.getName()!=ss.getName()){
//to delete
//existingfile.setTrashed(true);
folder.removeFile(existingfile);
}
}
//create new file
folder.createFile(fileName, csvFile);
}
}
I'd expect all files that don't share the same name as the spreadsheet in that folder to get removed, then a csv for each tab to get created. Instead, I get duplicates of each csv file.

Answer 1

Thanks a lot for you help. The while loop helped a bunch. Here's what worked for me in the end.
function saveAsCSV() {
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheets = ss.getSheets();
var file = DriveApp.getFileById(ss.getId());
var folder = file.getParents();
folder = folder.next();
// loop through files and delete ones with existing name
var xfiles=folder.getFiles();
while(xfiles.hasNext()) {
var fi=xfiles.next();
if(fi.getMimeType()!=MimeType.GOOGLE_SHEETS){fi.setTrashed(true);}
}
// create new csv files
for (var i = 0 ; i < sheets.length ; i++) {
var sheet = sheets[i];
// append ".csv" extension to the sheet name
fileName = sheet.getName() + ".csv";
// convert all available sheet data to csv format
var csvFile = convertRangeToCsvFile_(fileName, sheet);
//create new file
folder.createFile(fileName, csvFile);
}
};

Answer 2

Try this:
function trashOthers() {
var ss=SpreadsheetApp.getActive();
var shts=ss.getSheets();
var fldr=DriveApp.getFileById(ss.getId()).getParents();
var n=0;
while(fldr.hasNext()) {
var folder=fldr.next();
n++;
}
if(n>1){throw('More than one Folder');}
for (var i=0;i<shts.length;i++) {
var sh=shts[i];
var fileName=sh.getName() + ".csv";
var csvFile=convertRangeToCsvFile_(fileName, sh);
var xfiles=folder.getFiles();
while(xfiles.hasNext()) {
xfiles.next().setTrashed(true);
}
folder.createFile(fileName, csvFile);
}
}
Perhaps this is better:
function deleteOthers() {
var ss=SpreadsheetApp.getActiveSpreadsheet();
var shts=ss.getSheets();
var fldr=DriveApp.getFileById(ss.getId()).getParents();
var n=0;
while(fldr.hasNext()) {
var folder=fldr.next();
n++;
}
if(n>1){throw('More than one Folder');}
for (var i=0;i<shts.length;i++) {
var sh=shts[i];
var fileName=sh.getName() + ".csv";
var csvFile=convertRangeToCsvFile_(fileName, sh);
var xfiles=folder.getFiles();
while(xfiles.hasNext()) {
var fi=xfiles.next();
if(fi.getMimeType()!=MimeType.GOOGLE_SHEETS){fi.setTrashed(true);}
}
folder.createFile(fileName, csvFile);
}
}

Answer 3

I used deleteOthers() and trashothers() both are deleting the google form which writes data into csv