SpreadsheetApp.getActiveSpreadsheet() returning null - google-apps-script

Question

I need a quick function to loop through the rows of one of my sheets so I constructed this:
function getTotalsOf(name, type) {
var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(name);
var data = sheet.getDataRange().getValues();
var total = 0.00;
for (var i = 0; i < data.length; i++) {
if (data[i][0]== "") break;
if (data[i][2] == type) {
var temp = (Number(data[i][4]) + Number(data[i][5]) + Number(data[i][6])) * data [i][3];
total = Number(total) + total;
}
}
return total;
}
SpreadsheetApp.getActiveSpreadsheet() seems to return null when I try to execute the function. It also returns null when I try to get the spreadsheet by id. Am I missing something?
EDIT:
I retried using my spreadsheet id (https://docs.google.com/spreadsheets/d/STRINGFROMHERE/edit#gid=1235572150) with the same results.
function getTotalsOf(name, type) {
var sheet = SpreadsheetApp.openById("**STRINGFROMURL**").getSheetByName(name);
var data = sheet.getDataRange().getValues();
var total = 0.00;
for (var i = 0; i < data.length; i++) {
if (data[i][0]== "") break;
if (data[i][2] == type) {
var temp = (Number(data[i][4]) + Number(data[i][5]) + Number(data[i][6])) * data [i][3];
total = Number(total) + temp;
}
}
return total;
}

Answer 1

I think you just missed a few concepts with regard to looping through spreadsheets. Hope this demo will help and get you what you want. Always remember that rows and cols in spreadsheets starts with 1,1 not 0,0.
function loopThroughCells() {
var sheet = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
var data = sheet.getDataRange().getValues();
Logger.log(data[0].length);
for(var i=0; i< data.length; i++){
for(var j=0; j<data[i].length; j++){
if(data[i][j] == "HELIOS"){
if (data[i][j]== "") break;
Logger.log("HELIOS data found in range "+ (i+1) + " "+(j+1));
}
}
}
Log
[17-07-07 21:45:17:157 HKT] HELIOS data found in range 3 3