Delete only certain values not all values - google-apps-script

Question

The script deletes all values in the selected cells. I would like to write in exceptions if the value is something I don't want to be deleted.
Haven't tried anything because I'm not that good.
function Gtown() {
var spreadsheet = SpreadsheetApp.getActive();
spreadsheet.getRange('O38:P39').activate();
spreadsheet.getActiveRangeList().clear({contentsOnly: true, skipFilteredRows: true});
spreadsheet.getRange('A38:B39').activate();
spreadsheet.getActiveRangeList().clear({contentsOnly: true, skipFilteredRows: true});
spreadsheet.getRange('O26:P27').activate();
spreadsheet.getActiveRangeList().clear({contentsOnly: true, skipFilteredRows: true});
spreadsheet.getRange('I26:J27').activate();
spreadsheet.getActiveRangeList().clear({contentsOnly: true, skipFilteredRows: true});
spreadsheet.getRange('G26:H27').activate();
spreadsheet.getActiveRangeList().clear({contentsOnly: true, skipFilteredRows: true});
spreadsheet.getRange('A26:B27').activate();
spreadsheet.getActiveRangeList().clear({contentsOnly: true, skipFilteredRows: true});
spreadsheet.getRange('O16:P17').activate();
spreadsheet.getActiveRangeList().clear({contentsOnly: true, skipFilteredRows: true});
spreadsheet.getRange('I16:J17').activate();
spreadsheet.getActiveRangeList().clear({contentsOnly: true, skipFilteredRows: true});
spreadsheet.getRange('G16:H17').activate();
spreadsheet.getActiveRangeList().clear({contentsOnly: true, skipFilteredRows: true});
spreadsheet.getRange('A16:B17').activate();
spreadsheet.getActiveRangeList().clear({contentsOnly: true, skipFilteredRows: true});
spreadsheet.getRange('O6:P7').activate();
spreadsheet.getActiveRangeList().clear({contentsOnly: true, skipFilteredRows: true});
spreadsheet.getRange('I6:J7').activate();
spreadsheet.getActiveRangeList().clear({contentsOnly: true, skipFilteredRows: true});
spreadsheet.getRange('G6:H7').activate();
spreadsheet.getActiveRangeList().clear({contentsOnly: true, skipFilteredRows: true});
spreadsheet.getRange('A6:B7').activate();
spreadsheet.getActiveRangeList().clear({contentsOnly: true, skipFilteredRows: true});
};
No messages. I only want to delete certain values.

Answer 1

First of all, please, use a loop! Right now your script is very "heavy":
function Gtown() {
var ss = SpreadsheetApp.getActive();
var rl = ss.getRangeList(['A1:A5','B1:B5']); //put any Range references here;
var rs = rl.getRanges();
var opts = {contentsOnly: true, skipFilteredRows: true};
rs.forEach(function(range){
range.clear(opts);
});
}
Then, inside the forEach "loop", instead of unconditional cleanup, wrap clear() method in an if...else statement (Range values can be accessed via getValue() or getValues() method calls)

Answer 2

Try this:
function clearSelectedLocations() {
var ss=SpreadsheetApp.getActive();
var sh=ss.getActiveSheet();
var rA=['O38:P39','A38:B39','O26:P27','I26:J27','G26:H27','A26:B27','O16:P17','I16:J17','G16:H17','A16:B17','O6:P7','I6:J7','G6:H7','A6:B7'];
var rgA=sh.getRangeList(rA).getRanges();
for(var i=0;i<rgA.length;i++) {
rgA[i].clear({contentsOnly: true, skipFilteredRows: true});
}
}
Try this:
function clearSelectedLocations() {
var ss=SpreadsheetApp.getActive();
var sh=ss.getActiveSheet();
var rg=sh.getDataRange();
var vA=rg.getValues()
for(var i=0;i<vA.length;i++) {
if(sh.isRowHiddenByFilter(i+1)) {
continue;
}else{
for(var j=0;j<vA[i].length;j++) {
if(vA[i][j].toString()=="On Duty") {
sh.getRange(i+1,j+1).clear({contentsOnly: true});
}
}
}
}
If you have more than one values to clear:
function clearSelectedLocations() {
var ss=SpreadsheetApp.getActive();
var sh=ss.getActiveSheet();
var rg=sh.getDataRange();
var vA=rg.getValues();
var clA=["On Duty"];
for(var i=0;i<vA.length;i++) {
if(sh.isRowHiddenByFilter(i+1)) {
continue;
}else{
for(var j=0;j<vA[i].length;j++) {
if(clA.indexOf(vA[i][j].toString())>-1) {
sh.getRange(i+1,j+1).clear({contentsOnly: true});
}
}
}
}