Unable to return Array [Google apps script]

Question

We have a problem. The code we have now works, but we can't get the array to return on the html page. We are sending a number from the html page, and then the returnData function occurs. While it goes, it goes through loopsheetGewoon, and then it returns an array. The array is returned to returnData, and the function ends with the returnal of the array.

The problem is, that when we try to get the array to the html page so we can get individual data from the spreadsheet, it returns undefined. We have also tried passinga javascript value to google apps script code, but that didn't work.

function loopSheetGewoon(data, studentNr){
    var SpreadSheetKeyA = "1h8fDwCUUPHRdmTHu-5gMyqU294ENZxCZcHCNCuN6r_Y";
    var sheet1 = SpreadsheetApp.openById(SpreadSheetKeyA).getActiveSheet();
    var array = [];
    for (var y = 0; y < data.length; ++y ) {
        var datum = Utilities.formatDate(data[y][0], "CET", "dd-MM-yyyy hh:mm");
        var nummer = data[y][2];
        if(studentNr.equals(nummer)){
            for (var x = 0; x < 35; x++ ) {
                array.push(data[y][x]);
            }
            return array;        
        }    
    }
}

Below is the function that is initiated.

function returnData(stuNr){
    var SpreadSheetKeyA = "1h8fDwCUUPHRdmTHu-5gMyqU294ENZxCZcHCNCuN6r_Y";
    var sheet1 = SpreadsheetApp.openById(SpreadSheetKeyA).getActiveSheet();
    var data = sheet1.getDataRange().getValues();
    var array = [];
    array = loopSheetGewoon(data, stuNr);
    Logger.log(array);
    return array;
}

Below is the function we are running from the html page. When a button is clicked, it sends a number to the returnData function ( Which is stored as a string value). It should now fill up the variable d with the array, however it keeps returning undefined.

$("#oph").click(function ophalen(){
    var s = $("#nummer").val();
    var displayEl = document.getElementById("nummer");
    var d = [];
    alert(s);
    d = google.script.run.returnData(s);

    //for( var y = 0; y < d.length(); ++y){
        //var naam = data[y][1];
        //var studentnr = data[y][2];
        //var document = data[y][32];
    //}
    alert(d);
    var div = document.getElementById('block');
    div.innerHTML = naam;
});

So I am not sure what we are doing wrong, since the function itself works fine, up to the point until it returns to the html page.

Answer 1

Unfortunately, one of the documented limitations of google.script.run (still valid as of March 2019) is that you can't pass a Date object in any way, including as part of an array.

You can either call getDisplayValues() instead of getValues() on a range to only fetch an array of Strings to begin with, or you can convert Date objects to Strings by processing the getValues() array.