Google sheet + App Script : Rename every sheet if it meet criteria - datetime

Question

Hi I'm using this script to rename every sheet by inserting 'Copy of' in front of the existing sheet name where the text in cell 'B36' = 'SAFETY ANALISIS' and the date from cell 'K3'is older then 30 days. My issue is having to do with the date I can't quite figure how to do it. Cell 'K3' cell are in this format "1-Aug-2021" I think I need to convert the date in 'K3' to a number format.
Any help would be greatly appreciated
function getSheet() {
var sheets = SpreadsheetApp.getActiveSpreadsheet().getSheets();
var sum = 0;
for (var i = 0; i < sheets.length ; i++ ) {
var sheet = sheets[i];
var date = new Date();
var ageInDays = 30;
var threshold = new Date(
date.getFullYear(),
date.getMonth(),
date.getDate() - ageInDays)
.getTime();
var val = sheet.getRange('K3').getValue();
var val2 = sheet.getRange('B36').getValue();
if (val >= threshold && val2 == 'SAFETY ANALYSIS') {
var sheetName = sheet.getName()
sheet.setName('Copy Of '+sheetName)
}
}
}

Answer 1

You may want to wrap the value you get from cell K3 in a Date() constructor. That should work with spreadsheet dates as well as text strings that look like dates.
I think you have the comparison in val >= threshold the wrong way around. Try something like this:
function renameOldSafetyAnalysisSheets() {
const timeLimit = 30 * 24 * 60 * 60 * 1000; // 30 days
const now = new Date();
const sheets = SpreadsheetApp.getActive().getSheets();
sheets.forEach(sheet => {
if (sheet.getRange('K3').getValue() !== 'SAFETY ANALYSIS') {
return;
}
const date = new Date(sheet.getRange('B36').getValue());
if (!date.getTime()
|| now.getTime() - date.getTime() < timeLimit) {
return;
}
try {
sheet.setName('Copy of ' + sheet.getName());
} catch (error) {
;
}
});
}

Answer 2

function getSheet() {
const shts = SpreadsheetApp.getActive().getSheets();
let d = new Date();
let ageInDays = 30;
let threshold = new Date(d.getFullYear(),d.getMonth(),d.getDate() - ageInDays).valueOf();
shts.forEach(sh => {
let val = new Date(sh.getRange('K3').getValue()).valueOf();
let val2 = sh.getRange('B36').getValue();
if (val <= threshold && val2 == 'SAFETY ANALYSIS') {
sh.setName('Copy Of ' + sh.getName())
}
});
}