Uncaught TypeError: Cannot read property '1' of undefined (even though it is defined)

Question

So our teacher gave us the "Game Of Life" project. I was really proud of my project until I ran it and got the error "Uncaught TypeError: Cannot read property '1' of undefined". For those who don't know what Game Of Life is, it's a "game" where you have a matrix (here an 8x8 matrix) and some rules to define if each "person" (the numbers in the matrix) gets to live or not. 1 means alive and 0 means dead. I'll attach the whole project for reference, but here's the part with the error:

function process(matrix) { //creates the next generation

var neighbors = 0,
    position = '',
    nextgen = new Array(8); //the matrix has 8 rows
    for (i = 1; i <= 8; i++) {
        nextgen[i] = new Array(8);
        for (j = 1; j <= 8; j++) {
            neighbors = neighbors(matrix, i, j);

            //Game Rules
                if (neighbors < 2) {nextgen[i][j] = 0;
                } else if (neighbors == 2) {nextgen[i][j] = 1;
                } else if (neighbors <= 3) {nextgen[i][j] = nextgen[i][j];
                } else {nextgen[i][j] = 0;}
        }
    }
    return nextgen;
}

The error appears at if (neighbors < 2) {nextgen[i][j] = 0;}. Anyone have any ideas as to why? I defined nextgen[1][1] when I defined 8 arrays for nextgen[1], right?

Here's the whole project. the names and everything are in german, so please keep that in mind.

function berechne_nachbarn(matrixb, x, y) { //berechnet die Anzahl der Nachbarn fuer eine Zelle

var zelle = 0,
  nachbarn = 0,
  oben = 0,
  unten = 0,
  links = 0,
  rechts = 0;

//loesung fuer die Randzellen
 if (x == 1) {oben = 1} else {oben = x - 1}
 if (y == 1) {links = 1} else {links = y - 1}
 if (x == 8) {unten = 8} else {unten = x + 1}
 if (y == 8) {rechts = 8} else {rechts = y - 1}
 
for (i = oben; i <= unten; i++) {
 for (j = links; j <= rechts; j++) {
  zelle = parseInt (matrixb[i][j]);
  //loesung fuer leere Zellen
  if (isNaN(zelle)) {zelle = 0;}
  nachbarn = nachbarn + zelle;
 }//ende for j
}//ende for i
//die Zelle selbst ist nicht sein eigener Nachbar!
 nachbarn = nachbarn - matrixb[x][y];
 return nachbarn;
}//ende berechne_nachbarn;

function eingabe() {//erstellt Matrix

var spalte = 0,
  zeile = 0,
  ort = ''
  zelle = 0;
 brett = new Array(8); //8 Zeilen
 for (i = 1; i <= 8; i++) {
  brett[i] = new Array(8); //8 Spalten
  for (j = 1; j <= 8; j++) {
   ort = i + 'xx' + j;
    zelle = parseInt(document.formular.elements[ort].value);
    if (isNaN(zelle)) {zelle = 0;}
   brett[i][j] = zelle;
  }//ende for j
 }//ende for i
 return brett;
}//ende eingabe

function verarbeitung(matrix) {//Spielregeln und Verarbeitung

var nachbarn = 0,
  ort = '',
 nextgen = new Array(8); //neue Matrix fuer neue Generation
 for (i = 1; i <= 8; i++) {
  nextgen[i] = new Array(8);
  for (j = 1; j <= 8; j++) {
   nachbarn = berechne_nachbarn(matrix, i, j);
   
   //Spielregeln
    if (nachbarn < 2) {nextgen[i][j] = 0;
    } else if (nachbarn == 2) {nextgen[i][j] = 1;
    } else if (nachbarn <= 3) {nextgen[i][j] = nextgen[i][j];
    } else {nextgen[i][j] = 0;}
  }//ende for j
 }//ende for i
 return nextgen;
}//ende verarbeitung

function ausgabe(matrix) {//aendert die Werte im Formular

var ort = '';
 for (i = 1; i <= 8; i++) {
  for (j = 1; j <= 8; j++) {
   ort = i + 'xx' + j;
   document.formular.elements[ort].value = matrix[i][j];
  }//ende for j
 }//ende for i
}//ende ausgabe



 Game Of Life

user_10636077 · Answer

I found the problem guys. It's in the berechne_nachbarn function, where the program counts the neighbors of each cell on the game board. More specifically in this part:

if (y == 8) {rechts = 8} else {rechts = y - 1}

y - 1 should have been y + 1.

Ps. the program works now and I'm so proud of it ^_^

Uncaught TypeError: Cannot read property '1' of undefined (even though it is defined)

1 Answers