Problem
The OP enters 14022019 in an unformated cell. When the cell is formatted as a date, the value returned is 24 December 40290; the OP expected the date to be 14 February 2019.
Solution
- 1: format the cell as a date before data entry.
- 2: enter number with separators, such as 14/02/2019 or 14-02-2019
Explanation
When the OP types "14022019" into an unformatted cell, they intend that the input should be treated as a date (14 February 2019). However Google treats the contents at face value; there is no inference about date/time. So, when the cell is subsequently formatted as date, the raw value is converted to a date and the cell displays 24 December 40290.
The reason is that the Google Time Epoch began on 31 December 1899 00:00:00 (as opposed to the Unix Time Epoch, which is used by Javascript, which began on January 1, 1970 00:00:00). Secondly, Google measures date-time in days (as opposed to the Unix Epoch that measures elapsed seconds).
This is (roughly) how Google converts 14,022,019 to 24 December 40290.
- 14,022,019 "days", at a rough average of 365.245 days per year = approximately 38390.7 years.
- Add on 1899 for the Google Epoch. Running total = 40289.7 years. (roughly mid September 40290)
- Allow for adjustments for leap years 101.795 days = 0.3 (101.795/365.245); running total = 40290 years. (roughly 24 December 40290)
Note#1: there is a further complication.
The way that Sheets and Apps Script handle "dates" are very different.
- Sheets: the "date" unit is 1 day; The base date is 1899-12-30 0:00:00, getting the timezone from the spreadsheet settings.
- Apps Script (being based on JavaScript): the "date" unit is 1 millisecond. The base date is 1970-1-1 00:00:00 UTC.
Reference/Credit: Rubén
Note#2: My reference for the Google Epoch is (https://webapps.stackexchange.com/a/108119/196152)
Note#3: Broadly date/time conversions are based on 3,600 seconds per hour, 86,400 seconds per day, 31,556,926 second per year and 365.24 days per year.
UPDATE - 20 Feb 2019
The OP asks, quite rightly, "so how do I convert the existing cells?"
The code to make the conversion is straightforward:
- convert the number to a string
- slice the string into components for Day, Month and Year
- use the components to create a new date
- update the cell with the date
The range to be converted is an potential issue. What is the range, is the range always the the same size, etc? The following code enables an interface for the user to choose a range. The range can then be converted. Arguably this element wasn't essential, but does provide a more flexible, if not elegant, solution.
Code.gs
function onOpen(){
SpreadsheetApp.getUi()
.createMenu("Date Convert")
.addItem("Convert", "selRange")
.addToUi();
}
function selRange()//run this to get everything started. A dialog will be displayed that instructs you to select a range.
{
var output=HtmlService.createHtmlOutputFromFile('pickRange').setWidth(300).setHeight(200).setTitle('Convert to dates');
SpreadsheetApp.getUi().showModelessDialog(output, 'Convert Numbers to Dates');
}
function selCurRng()
{
var sso=SpreadsheetApp.getActive();
var sh0=sso.getActiveSheet();
var rg0=sh0.getActiveRange();
var rng0A1=rg0.getA1Notation();
rg0.setBackground('#FFC300');
return rng0A1;
}
function clrRange(range)
{
var sso=SpreadsheetApp.getActive();
var sh0=sso.getActiveSheet();
var rg0=sh0.getRange(range);
rg0.setBackground('#ffffff');
}
function convertnumbertodate(crange){
// establish spreadsheet credentials
var ss1=SpreadsheetApp.getActive();
var sh1=ss1.getActiveSheet();
// get the range so that rows and columns can be calculated
var rg1=sh1.getRange(crange);
// get number of columns
var numColumns = rg1.getNumColumns();
// if more than one column chosen, stop the process.
if (numColumns !=1){
//Logger.log("DEBUG: Number of columns in range = "+numColumns); // DEBUG
var message = "Too Many Columns; one column only";
return message;
}
// get the first row and the number of rows
var rowqty = 1;
var rownum = rg1.getRow();
// Logger.log("DEBUG: first row = "+rownum);//DEBUG
var rowqty = rg1.getNumRows();
// Logger.log("DEBUG: Number of rows = "+rowqty); //DEBUG
// get the values - different syntax for a single cell vs range
if (rowqty !=1){
// Multiple cells - uset GetValues
var rangevalues = rg1.getValues();
}
else {
// single cell, use getValue
var rangevalues = rg1.getValue();
}
//Logger.log("DEBUG: Values = "+rangevalues); //DEBUG
// create array for temporary storage
var newvalues = [];
// loop through the values
for (var i=0; i< rowqty; i++){
// different treatment for single cell value
if (i!=0 && rowqty !=1){
// multiple cells
var nstring = rangevalues[i].toString();
}
else {
// single value cell
var nstring = rangevalues.toString();
}
Logger.log("DEBUG: Value of the string is = "+nstring); //DEBUG
// slice the string in day, month and year
var daystring = nstring.slice(0, 2);
var monthstring = nstring.slice(2, 4);
var yearstring = nstring.slice(4, 8);
//calculate the date
var pubdate = new Date(yearstring, monthstring - 1, daystring);
//Logger.log("DEBUG: the date is "+pubdate); //DEBUG
// push the value onto the aray
newvalues.push([pubdate]);
}
// set the value(s)
if (rowqty !=1){
// Multiple cells - uset GetValues
rg1.setValues(newvalues)
}
else {
// single cell, use getValue
rg1.setValue(newvalues);
}
//rg1.setValues(newvalues);
var message = "Update complete";
rg1.setBackground('#ffffff');
return message;
}
pickRange.html
<!DOCTYPE html>
<html>
<head>
<base target="_top">
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script>
var grange='';
function selectRange()
{
$('#btn1').prop('disabled',true);
$('#btn2').prop('disabled',false);
google.script.run
.withSuccessHandler(setResponse)
.selCurRng();
}
function setResponse(r)
{
grange=r;
var msg='Selected range: ' + r+". Ready to convert";
$('#instr').css('display','none');
$('#rsp').text(msg);
}
function convert2date()
{
$('#btn1').prop('disabled',false);
$('#btn2').prop('disabled',false);
google.script.run
.withSuccessHandler(setResponse02)
.convertnumbertodate(grange);
}
function setResponse02(q)
{
qnumber=q;
var msg= q;
$('#instr').css('display','none');
$('#rsp').text(msg);
}
function clearAndClose()
{
google.script.run.clrRange(grange);
google.script.host.close();
}
console.log('My Code');
</script>
</head>
<body>
<div id="rsp"></div>
<div id="instr">Select range - <b>One column limit</b></div>
<br/>
<input type="button" id="btn1" value="1 - Select a range" onClick="selectRange();" />
<br />
<input type="button" id="btn3" value="2 - Convert numbers to dates" onClick="convert2date();" />
<br />
<input type="button" id="btn2" value="close" onClick="clearAndClose();"; disabled="true" />
</body>
</html>
Credit
//Prompt user for range in .gs function, pass array to html script and re-focus on the HTML dialog
//credit answer by Cooper - https://stackoverflow.com/a/45427670/1330560
ADDENDUM
If the range in which pseudo-dates are entered is know, and is non-changing, then the code to manage it is simplified
function onEdit(e) {
// establish spreadsheet credentials
var ss1 = SpreadsheetApp.getActive();
var sh1 = ss1.getActiveSheet();
// get the onEdit parameters
var debug_e = {
authMode: e.authMode,
range: e.range.getA1Notation(),
source: e.source.getId(),
user: e.user,
value: e.value,
oldValue: e.oldValue
};
//Logger.log("AuthMode: "+debug_e.authMode+"\n, Range: "+debug_e.range+"\n, source: "+debug_e.source+"\n, user: "+debug_e.user+"\n, value: "+debug_e.value+"\n, old value: "+debug_e.oldValue);
// Note the range for data entry is known and fixed.
// it is "D3:D31"
// Target range for converting numbers to dates
// set the column
var column = 4; // column D
// get the first row and the number of rows
var rowqty = 29;
var rowfirst = 3;
var rowlast = 31;
//Logger.log("DEBUG: first row = "+rowfirst+", last row = "+rowlast+", number of rows = "+rowqty);//DEBUG
// get detail of the edited cell
var editColumn = e.range.getColumn();
var editRow = e.range.getRow();
//Logger.log("DEBUG: edited column = "+editColumn+", edited row "+editRow);//DEBUG
//test if the edited cell falls into the target range
if (editColumn == 4 && editRow >= rowfirst && editRow <= rowlast) {
// the edit was in the target range
var nstring = e.value.toString();
//Logger.log("DEBUG: Value of the string is = "+nstring); //DEBUG
// slice the string in day, month and year
var daystring = nstring.slice(0, 2);
var monthstring = nstring.slice(2, 4);
var yearstring = nstring.slice(4, 8);
//calculate the date
var pubdate = new Date(yearstring, monthstring - 1, daystring);
//Logger.log("DEBUG: the date is "+pubdate); //DEBUG
e.range.setValue(pubdate)
} else {
//Logger.log("DEBUG: Nothing to see here; this cell not in the target range");//DEBUG
}
}
