Comparing Dates in Google Apps Scrips through For Loops

Question

I'm trying to compare a user specified date against a date in a databank on another sheet. The script should return the specified columns of any row with the matching date. Currently, it returns all of the data. It seems like the IF statement is always reading as true, regardless of the values. The logs show the values are different. Why might this IF statment always be returning true, and thus returning all databank rows? Code Below:

function search() 
{

//clears contents in search sheet (sheet1)
var app=SpreadsheetApp;
var WorkSheet =  app.getActiveSpreadsheet().getSheetByName("Sheet1");
WorkSheet.getRange("A2:D50").clearContent();

//store date search value - getrange x and get it's value
var DateSearch = WorkSheet.getRange(1,2).getValue();
//view variable for testing
Logger.log(DateSearch);

//data sheet lastrow variable
var dataSheet = app.getActiveSpreadsheet().getSheetByName("Form Responses 
1");
var a = dataSheet.getDataRange().getNumRows();
//view variable for testing
Logger.log(a);

//var i is looper
var i;
var dataI;
var copyValue;
//view if statement value for testing

for(i=2;i<=a;i++)
{
Logger.log(i);
dataI = dataSheet.getRange(i,1).getValue();
Logger.log(dataI); 
Logger.log(DateSearch);

if (dataI = DateSearch)
{
  // returns values in variable row and first 2 columns if condition is met
  copyValue = dataSheet.getRange(i, 1, 1, 2).getValues();
  //test copyValue
  Logger.log(copyValue);
  WorkSheet.getRange(i,1,1,2).setValues(copyValue);
    }
  }
}

Answer 1

How about this modification?

Modification points:

• In the case of if (dataI = DateSearch), when DateSearch has a value, it always works as true. By this, the script when if is true works every time.
• When 2 date values are compared, please compare them by converting to number.
  • This is mentioned from @tehhowch

Modified script:

In order to reflect above points, please modify as follows and try to run again. The former and latter compare the unix time and each year, month and day, respectively. You can choose one of 2 samples.

From:

if (dataI = DateSearch)

To:

if (new Date(dataI).getTime() === new Date(DateSearch).getTime())

Or

To:

if (new Date(dataI).getFullYear() === new Date(DateSearch).getFullYear() &&
    new Date(dataI).getMonth() === new Date(DateSearch).getMonth() &&
    new Date(dataI).getDate() === new Date(DateSearch).getDate())

Other modification:

By the way, from your script and sample spreadsheet, it is considered that when the number of data becomes large, the process time will become long. So as the other modification for this situation, how about this? But I'm not sure whether this is useful for your situation. So please think of this as a sample script.

function search() {
  var app=SpreadsheetApp;
  var WorkSheet =  app.getActiveSpreadsheet().getSheetByName("Sheet1");
  WorkSheet.getRange("A2:D50").clearContent();
  var DateSearch = WorkSheet.getRange(1,2).getValue();
  var dataSheet = app.getActiveSpreadsheet().getSheetByName("Form Responses 1");

// Below script was modified.
  var dataI = dataSheet.getDataRange().offset(1, 0).getValues();
  var copyValue = dataI.map(function(e, i) {
    return new Date(e[0]).getTime() === new Date(DateSearch).getTime() ? e : ["", ""];
  });
  WorkSheet.getRange(2,1,copyValue.length,copyValue[0].length).setValues(copyValue);
}

References :

• Compare two dates with JavaScript

If this result was not what you want, please tell me. I would like to modify it.

Added:

This modification script puts the retrieved values without the empty rows to the row 2.

function search() {
  var app=SpreadsheetApp;
  var WorkSheet =  app.getActiveSpreadsheet().getSheetByName("Sheet1");
  WorkSheet.getRange("A2:D50").clearContent();
  var DateSearch = WorkSheet.getRange(1,2).getValue();
  var dataSheet = app.getActiveSpreadsheet().getSheetByName("Form Responses 1");

// Below script was modified.
  var dataI = dataSheet.getDataRange().offset(1, 0).getValues();
  var copyValue = dataI.filter(function(e) { // Modified
    return new Date(e[0]).getTime() === new Date(DateSearch).getTime(); // Modified
  });
  WorkSheet.getRange(2,1,copyValue.length,copyValue[0].length).setValues(copyValue);
}