Create script.js

script.js

@@ -0,0 +1,172 @@
+var board;
+var score = 0;
+var rows = 4;
+var columns = 4;
+
+window.onload = function() {
+    setGame();
+}
+
+function setGame() {
+    board = [[0, 0, 0, 0],
+             [0, 0, 0, 0],
+             [0, 0, 0, 0],
+             [0, 0, 0, 0]]
+
+    for (let r = 0; r < rows; r++) {
+        for (let c = 0; c < columns; c++) {
+            let tile = document.createElement("div");
+            tile.id = r.toString() + "-" + c.toString();
+            let num = board[r][c];
+            updateTile(tile, num);
+            document.getElementById("board").append(tile);
+        }
+    }
+    //create 2 to begin the game
+    setTwo();
+    setTwo();
+
+}
+
+function updateTile(tile, num) {
+    tile.innerText = "";
+    tile.classList.value = ""; //clear the classList
+    tile.classList.add("tile");
+    if (num > 0) {
+        tile.innerText = num.toString();
+        if (num <= 4096) {
+            tile.classList.add("x"+num.toString());
+        } else {
+            tile.classList.add("x8192");
+        }                
+    }
+}
+
+document.addEventListener('keyup', (e) => {
+    if (e.code == "ArrowLeft") {
+        slideLeft();
+        setTwo();
+    }
+    else if (e.code == "ArrowRight") {
+        slideRight();
+        setTwo();
+    }
+    else if (e.code == "ArrowUp") {
+        slideUp();
+        setTwo();
+
+    }
+    else if (e.code == "ArrowDown") {
+        slideDown();
+        setTwo();
+    }
+    document.getElementById("score").innerText = score;
+})
+
+function filterZero(row){
+    return row.filter(num => num != 0); //create new array of all nums != 0
+}
+
+function slide(row) {
+    //[0, 2, 2, 2] 
+    row = filterZero(row); //[2, 2, 2]
+    for (let i = 0; i < row.length-1; i++){
+        if (row[i] == row[i+1]) {
+            row[i] *= 2;
+            row[i+1] = 0;
+            score += row[i];
+        }
+    } //[4, 0, 2]
+    row = filterZero(row); //[4, 2]
+    //add zeroes
+    while (row.length < columns) {
+        row.push(0);
+    } //[4, 2, 0, 0]
+    return row;
+}
+
+function slideLeft() {
+    for (let r = 0; r < rows; r++) {
+        let row = board[r];
+        row = slide(row);
+        board[r] = row;
+        for (let c = 0; c < columns; c++){
+            let tile = document.getElementById(r.toString() + "-" + c.toString());
+            let num = board[r][c];
+            updateTile(tile, num);
+        }
+    }
+}
+
+function slideRight() {
+    for (let r = 0; r < rows; r++) {
+        let row = board[r];         //[0, 2, 2, 2]
+        row.reverse();              //[2, 2, 2, 0]
+        row = slide(row)            //[4, 2, 0, 0]
+        board[r] = row.reverse();   //[0, 0, 2, 4];
+        for (let c = 0; c < columns; c++){
+            let tile = document.getElementById(r.toString() + "-" + c.toString());
+            let num = board[r][c];
+            updateTile(tile, num);
+        }
+    }
+}
+
+function slideUp() {
+    for (let c = 0; c < columns; c++) {
+        let row = [board[0][c], board[1][c], board[2][c], board[3][c]];
+        row = slide(row);
+        for (let r = 0; r < rows; r++){
+            board[r][c] = row[r];
+            let tile = document.getElementById(r.toString() + "-" + c.toString());
+            let num = board[r][c];
+            updateTile(tile, num);
+        }
+    }
+}
+
+function slideDown() {
+    for (let c = 0; c < columns; c++) {
+        let row = [board[0][c], board[1][c], board[2][c], board[3][c]];
+        row.reverse();
+        row = slide(row);
+        row.reverse();
+        for (let r = 0; r < rows; r++){
+            board[r][c] = row[r];
+            let tile = document.getElementById(r.toString() + "-" + c.toString());
+            let num = board[r][c];
+            updateTile(tile, num);
+        }
+    }
+}
+
+function setTwo() {
+    if (!hasEmptyTile()) {
+        return;
+    }
+    let found = false;
+    while (!found) {
+        //find random row and column to place a 2 in
+        let r = Math.floor(Math.random() * rows);
+        let c = Math.floor(Math.random() * columns);
+        if (board[r][c] == 0) {
+            board[r][c] = 2;
+            let tile = document.getElementById(r.toString() + "-" + c.toString());
+            tile.innerText = "2";
+            tile.classList.add("x2");
+            found = true;
+        }
+    }
+}
+
+function hasEmptyTile() {
+    let count = 0;
+    for (let r = 0; r < rows; r++) {
+        for (let c = 0; c < columns; c++) {
+            if (board[r][c] == 0) { //at least one zero in the board
+                return true;
+            }
+        }
+    }
+    return false;
+}