Set array size equal to number of files in a folder

Question

I'm trying to create a google script that counts the number of files in a folder, then assigns this number to a variable that can be used to define the size of an array.

1. ID folder
2. get files in folder
3. set counter = filecount
4. use counter to define array size

my attempt:

function setarraytofilecount() {
var dealspsfolderid = "ID goes here";
var dealspsfolder = DriveApp.getFolderById(dealspsfolderid);
var ssfiles = dealspsfolder.getFiles();

var count, file;

count = 0;

while (ssfiles.hasNext()) {
count++;
file = ssfiles.next();
}

var nesteddata = new Array(count); 

I'm expecting to create an array with a size equal to the number of files in the folder, but I don't believe this is what is happening.

The script runs, there is more after this I'm leaving out for simplicity. I think the problem may be that I cannot use the variable count in new Array(), is that correct?

---

Here is the whole script:

function autoUpdateFiles() {

// set the folder to pull files from
var dealspsfolderid = "removed";
var dealspsfolder = DriveApp.getFolderById(dealspsfolderid);
var ssfiles = dealspsfolder.getFiles();
var trackerurl = "removed";
var sstoupdate = SpreadsheetApp.openByUrl(trackerurl);

// set the sheet to update
var sheettoupdate = sstoupdate.getSheetByName('AutoTracker');

// indicates current deal row
var rowcounter = 0;

// get number of files in the folder which we can use to define array size
var count,file;//Define variables without assigning a value
count = 0;
while (ssfiles.hasNext()) {
 count++;
 file = ssfiles.next();
}

// nested array of row data arrays. i.e. each index is an array of a row 
var nesteddata = new Array(); 
nesteddata.length = count;
for(i = 0; i < nesteddata.length; i++){
  nesteddata[i] = new Array(158);
}

// nested array of row data arrays. i.e. each index is an array of a row 
var URLarray = new Array(); 
URLarray.length = count;
for(i = 0; i < URLarray.length; i++){
 URLarray[i] = new Array(1);
}

// iterate through each file
while (ssfiles.hasNext()) {

// pull the next file
var file = ssfiles.next();

// get the url       
Logger.log(file.getUrl());

// activate the sheet
var spreadsheet = SpreadsheetApp.open(file);
var activesheet = spreadsheet.getSheets()[0].activate();

// pull values from the files 
// ranges are ROW, COLUMN
var URL = file.getUrl();  
var colC = activesheet.getRange(3, 3, 158 ,3).getValues();           

// transition the vertical multidimensional array returned into flat array for a row
for(var i = 0; i < colC.length; i++){
   nesteddata[rowcounter][i]=colC[i][0];
  }

 for(var i = 0; i < URLarray.length; i++){
   URLarray[rowcounter]= [URL];    
  }
rowcounter ++;
}

// write out to the sheet  
sheettoupdate.getRange(2,1,nesteddata.length,1).setValues(URLarray);
sheettoupdate.getRange(2,2,nesteddata.length,158).setValues(nesteddata);

Answer 1

You can use the length property to set the number of elements in an array:

var nesteddata = new Array(); 

nesteddata.length = count;
Logger.log(nesteddata);
Logger.log(nesteddata.length);

The array will look like this:

[null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null]

It will have the number of elements in it, with all the elements having a null value