Deleting sheets not found in lookup - google-apps-script

Question

I am trying to delete unneeded sheets from a template once relevant information has been copied across. To do this I am looking up the sheet name with a check list. If the lookup returns a value of 0.0 then I want to delete the sheet.
function myFunction() {
var studentsheet = SpreadsheetApp.openById('1Qj9T002nF6SbJRq-iINL2NisU7Ld0kSrQUkPEa6l31Q').;
var sheetsCount = studentsheet.getNumSheets();
var sheets = studentsheet.getSheets();
for (var i = 0; i < sheetsCount; i++){
var sheet = sheets[i];
var sheetName = sheet.getName();
Logger.log(sheetName);
var index = match(sheetName);
Logger.log(index);
if (index = "0.0"){
var ss = studentsheet.getSheetByName(sheetName).activate();
ss.deleteactivesheet();
}
else {}
}
function match(subject) {
var sourcesheet = SpreadsheetApp.openById('14o3ZG9gQt9RL0iti5xJllifzNiLuNxWDwTRyo-x9STI').getSheetByName("Sheet6").activate();
var lookupvalue = subject;
var lookuprange = sourcesheet.getRange(2, 2, 14, 1).getValues().map(function(d){ return d[0] });
var index = lookuprange.indexOf(subject)+1;
return index;
}
};
The problem is at the end when trying to delete the sheet. I have amended the code so it selects the sheet and makes it active but in the next line I am not allowed to call .deleteactivesheet(). Does anyone know how I can write this end part where I can select the sheet based on the index score being 0 and then delete it?

Answer 1

To delete a Sheet from a Spreadsheet, there are two applicable Spreadsheet class methods (as always, spelling and capitalization matter in JavaScript):
Spreadsheet#deleteSheet, which requires a Sheet object as its argument
Spreadsheet#deleteActiveSheet, which takes no arguments
The former is suitable for any type of script, and any type of trigger, while the latter only makes sense from a bound script working from a UI-based invocation (either an edit/change trigger, menu click, or other manual execution), because "activating" a sheet is a nonsense operation for a Spreadsheet resource that is not open in a UI with an attached Apps Script instance.
The minimum necessary modification is thus:
var index = match(sheet);
if (index === 0) { // if Array#indexOf returned -1 (not found), `match` returned -1 + 1 --> 0
studentsheet.deleteSheet(sheet);
}
A more pertinent modification would be something like:
function deleteNotFoundSheets() {
const studentWb = SpreadsheetApp.openById("some id");
const lookupSource = getLookupRange_(); // assumes the range to search doesn't depend on the sheets that may be deleted.
studentWb.getSheets().filter(function (s) {
return canDelete_(lookupSource, s.getName());
}).forEach(function (sheetToDelete) {
studentWb.deleteSheet(sheetToDelete);
});
}
function getLookupRange_() {
const source = SpreadsheetApp.openById("some other id");
const sheet = source.getSheetByName("some existing sheet name");
const r = sheet.getRange(...);
return r.getValues().map(...);
}
function canDelete_(lookupRange, subject) {
/** your code that returns true if the subject (the sheet name) should be deleted */
}
This modification uses available Array class methods to simplify the logic of your code (by removing iterators whose only purpose is to iterate, and instead expose the contained values to the anonymous callback functions). Basically, this code is very easily understood as "of all the sheets, we want these ones (the filter), and we want to do the same thing to them (the forEach)"
Additional Reading:
JavaScript comparison operators and this (among others) SO question
Array#filter
Array#forEach

Answer 2

If just like me you have been struggling to find a working example of #tehhowch above solution, here it is:
function deleteSheetsWithCriteria() {
let ss = SpreadsheetApp.getActiveSpreadsheet(),
sheetList = ss.getSheetByName('List'),
list = sheetList.getRange('A1:A'+sheetList.getLastRow()),
lookupRange = list.getValues().map(function(d){ return d[0] }) + ',List'; // List of sheets NOT to delete + lookuprange sheet
Logger.log(lookupRange)
//Delete all sheets except lookupRange
ss.getSheets().filter(function (sheet) {
return deleteCriteria_(lookupRange, sheet.getName());
}).forEach(function (sheetToDelete) {
ss.deleteSheet(sheetToDelete);
});
}
function deleteCriteria_(lookupRange, sheet) {
var index = lookupRange.indexOf(sheet);
Logger.log(index)
if (index > 0) {0} else {return index}; // change line 19 to 'return index;' only, if you want to delete the sheets in the lookupRange, rember to remove the lookupRange in variable LookupRage
}