I'm programming a checkers game for a high school project. I have a weird variable behaviour and I can't figure out why it's happening. Let me show you the code:
var player = 1;
var lastClicked;
var wasClicked = false;
var isEmpty = new Array(8);
for (var i = 0; i < 8; i++) {
isEmpty[i] = new Array(8);
for (var j = 0; j < 8; j++) {
isEmpty[i][j] = true;
}
}
function CreateBoard() {
var board = document.createElement("table");
board.cellSpacing = 0;
for (var i = 0; i < 8; i++) {
var tr1 = document.createElement("tr");
for (var j = 0; j < 8; j++) {
var td1 = document.createElement("td");
td1.setAttribute("id", "td" + i + j);
td1.addEventListener("click", function () { CheckIandJForLater(i, j); });
if (i % 2 == 0) {
if (j % 2 == 0)
td1.style.backgroundColor = "beige";
else
td1.style.backgroundColor = "black";
}
else {
if (j % 2 == 0)
td1.style.backgroundColor = "black";
else
td1.style.backgroundColor = "beige";
}
tr1.appendChild(td1);
}
board.appendChild(tr1);
}
document.body.appendChild(board);
}
function CheckIandJForLater(i, j) { // A function which is meant to show the weird behavior, which prevents me from using function I want to use in the event listener
alert("Function i: " + i);
alert("Function j: " + j);
}
function DeployPieces() {
CreateBoard();
var pieceIndex = 1;
for (var i = 0; i < 8; i++) {
if (i < 3) {
if (i % 2 == 0) {
for (var j = 1; j < 8; j += 2) {
var td1 = document.getElementById("td" + i + j);
var circle1 = document.createElement("span");
circle1.setAttribute("class", "redCircle");
circle1.setAttribute("id", "circle" + i + j);
wasFilled = true;
circle1.setAttribute("onclick", "AlertToPressOnSquare(); lastClicked = this; wasClicked = true;");
td1.appendChild(circle1);
isEmpty[i][j] = false;
}
}
else {
for (var j = 0; j < 8; j += 2) {
var td2 = document.getElementById("td" + i + j);
var circle2 = document.createElement("span");
circle2.setAttribute("class", "redCircle");
circle2.setAttribute("id", "circle" + i + j);
wasFilled = true;
circle2.setAttribute("onclick", "AlertToPressOnSquare(); lastClicked = this; wasClicked = true;");
td2.appendChild(circle2);
isEmpty[i][j] = false;
}
}
}
else if (i > 4) {
if (i % 2 == 0) {
for (var j = 1; j < 8; j += 2) {
var td3 = document.getElementById("td" + i + j);
var circle3 = document.createElement("span");
circle3.setAttribute("class", "whiteCircle");
circle3.setAttribute("id", "circle" + i + j);
wasFilled = true;
circle3.setAttribute("onclick", "AlertToPressOnSquare(); lastClicked = this; wasClicked = true;");
td3.appendChild(circle3);
isEmpty[i][j] = false;
}
}
else {
for (var j = 0; j < 8; j += 2) {
var td4 = document.getElementById("td" + i + j);
var circle4 = document.createElement("span");
circle4.setAttribute("class", "whiteCircle");
circle4.setAttribute("id", "circle" + i + j);
wasFilled = true;
circle4.setAttribute("onclick", "AlertToPressOnSquare(); lastClicked = this; wasClicked = true;");
td4.appendChild(circle4);
isEmpty[i][j] = false;
}
}
}
}
}
function AlertToPressOnSquare() {
alert("Player " + player + ", please press on the square to which you would like to move the piece");
if (player == 1)
player = 2;
else if (player == 2)
player = 1;
}
function MoveToSquare(i, j) { //The function I want to use in the td1 event listener
if (wasClicked && isEmpty[i][j]) {
var lastClickedId = lastClicked.getAttribute("id");
var lastClickedLocation = lastClickedId[6] + lastClickedId[7];
var v1 = parseInt(lastClickedId[6], 10);
var v2 = parseInt(lastClickedId[7], 10);
var tdFrom = document.getElementById("td" + lastClickedLocation);
var tdTo = document.getElementById("td" + i.toString() + j.toString());
if (lastClicked.getAttribute("class") == "whiteCircle") {
if (v1 == i - 1 && (v2 == j - 1 || v2 == j + 1)) {
tdFrom.removeChild(lastClicked);
tdTo.appendChild(lastClicked);
}
}
else if (lastClicked.getAttribute("class") == "redCircle") {
if (v1 == i + 1 && (v2 == j - 1 || v2 == j + 1)) {
tdFrom.removeChild(lastClicked);
tdTo.appendChild(lastClicked);
}
}
alert("Player " + player + ", please press on the piece you would like to move");
wasClicked = false;
}
}
So, the weird behavior is as follows: Every time I click on a td in the table and run the CheckIandJForLater function, I get the value 8 for both i and j. They should not get these values, as i and j are supposed to be updated in the for loop. Moreover, they should never reach the value of 8, since both the loops run between 0 and 7.
It's also worth noting that if I put alert(i); and alert(j); regularly, without the CheckIAndJForLater function, their values are printed fine.
I really struglle in finding out how to solve this weird behavior. May someone help me? Thank you.
Why is that behavior happening? Is there a solution?