Develop Reference

Box moving out of grid JavaScript

I have a yellow box in a grid. When click button 'UP' the yellow box is going one box UP. How can I stop the yellow box when it arrives at the edge? I do not want it to go out of the grid.
let moveCounter = 0;
var grid = document.getElementById("grid-box");
for (var i = 1; i <= 100; i++) {
var square = document.createElement("div");
square.className = 'square';
square.id = 'square' + i;
grid.appendChild(square);
}
var playerTwo = [];
while (playerTwo.length < 1) {
var randomIndex = parseInt(99 * Math.random());
if (playerTwo.indexOf(randomIndex) === -1) {
playerTwo.push(randomIndex);
var drawPtwo = document.getElementById('square' + randomIndex);
$(drawPtwo).addClass("p-1")
}
};
$('#button_up').on('click', function() {
moveCounter += 1;
$pOne = $('.p-1')
var id = $pOne.attr('id')
var idNumber = +id.slice(6);
var idMove = idNumber - 10
var idUpMove = 'square' + idMove;
$pOne.removeClass('p-1');
$('#' + idUpMove).addClass('p-1');
});
#grid-box {
width: 400px;
height: 400px;
margin: 0 auto;
font-size: 0;
position: relative;
}
#grid-box>div.square {
font-size: 1rem;
vertical-align: top;
display: inline-block;
width: 10%;
height: 10%;
box-sizing: border-box;
border: 1px solid #000;
}
.p-1{
background-color: yellow;
}
<div id="grid-box"></div>
<div class="move">
<button id="button_up">UP</button>
<br>
</div>
<script src="https://code.jquery.com/jquery-1.12.4.js"></script>
I am new to Javascript / jQuery. Any help will be much appreciated ! Thank you

let moveCounter = 0;
var grid = document.getElementById("grid-box");
for (var i = 1; i <= 100; i++) {
var square = document.createElement("div");
square.className = 'square';
square.id = 'square' + i;
grid.appendChild(square);
}
var playerTwo = [];
while (playerTwo.length < 1) {
var randomIndex = parseInt(99 * Math.random());
if (playerTwo.indexOf(randomIndex) === -1) {
playerTwo.push(randomIndex);
var drawPtwo = document.getElementById('square' + randomIndex);
$(drawPtwo).addClass("p-1")
}
};
$('#button_up').on('click', function() {
moveCounter += 1;
$pOne = $('.p-1')
var id = $pOne.attr('id')
var idNumber = +id.slice(6);
var idMove = idNumber - 10;
if(idMove < 0){idMove +=10;}
var idUpMove = 'square' + idMove;
$pOne.removeClass('p-1');
$('#' + idUpMove).addClass('p-1');
});
#grid-box {
width: 400px;
height: 400px;
margin: 0 auto;
font-size: 0;
position: relative;
}
#grid-box>div.square {
font-size: 1rem;
vertical-align: top;
display: inline-block;
width: 10%;
height: 10%;
box-sizing: border-box;
border: 1px solid #000;
}
.p-1{
background-color: yellow;
}
<div id="grid-box"></div>
<div class="move">
<button id="button_up">UP</button>
<br>
</div>
<script src="https://code.jquery.com/jquery-1.12.4.js"></script>
Here I have added the condition which restrict box to out of the grid
if(idMove < 0){idMove +=10;}
if movable position is in the minus then it again initialise it existing position.

You can add a check to stop it from moving out of the squares
var idMove = idNumber - 10
if(idMove > 0){
// do all the moving stuffs
}

$('#button_up').on('click', function() {
moveCounter += 1;
$pOne = $('.p-1')
var id = $pOne.attr('id')
var idNumber = +id.slice(6);
var idMove = idNumber - 10;
if(idMove > 0) {
var idUpMove = 'square' + idMove;
$pOne.removeClass('p-1');
$('#' + idUpMove).addClass('p-1');
}
});

You can use an if statement to check idMove > 0) If it is, then you can move your square, if it isn't then you shouldn't move your square. it will be undefined, and so you can run your code only when pOne's id is not undefined.
See example below:
let moveCounter = 0;
var grid = document.getElementById("grid-box");
for (var i = 1; i <= 100; i++) {
var square = document.createElement("div");
square.className = 'square';
square.id = 'square' + i;
grid.appendChild(square);
}
var playerTwo = [];
while (playerTwo.length < 1) {
var randomIndex = parseInt(99 * Math.random());
if (playerTwo.indexOf(randomIndex) === -1) {
playerTwo.push(randomIndex);
var drawPtwo = document.getElementById('square' + randomIndex);
$(drawPtwo).addClass("p-1")
}
};
$('#button_up').on('click', function() {
moveCounter += 1;
$pOne = $('.p-1')
var id = $pOne.attr('id')
var idNumber = +id.slice(6);
var idMove = idNumber - 10
if (idMove > 0) {
var idUpMove = 'square' + idMove;
$pOne.removeClass('p-1');
$('#' + idUpMove).addClass('p-1');
}
});
#grid-box {
width: 400px;
height: 400px;
margin: 0 auto;
font-size: 0;
position: relative;
}
#grid-box>div.square {
font-size: 1rem;
vertical-align: top;
display: inline-block;
width: 10%;
height: 10%;
box-sizing: border-box;
border: 1px solid #000;
}
.p-1 {
background-color: yellow;
}
<div id="grid-box">
</div>
<div class="move">
<button id="button_up">UP</button><br>
</div>
<script src="https://code.jquery.com/jquery-1.12.4.js"></script>

Minefield with JS gone wrong

I'm creating a minefiled game and I'm trying to put 10 bombs in a random location each time. The problem is that sometimes 2 or more bombs can be placed in the same block, resulting in less than 10 bombs in the game. How can I prevent this?
I've already tried saving all the bombs locations in an array and each time compare the new bomb location to all the past ones, but id didn't work.
Here is my code:
var number_of_blocks = 0;
var number_of_bombs = 10;
var minefield_width = 500;
var minefield_height = 500;
var block_width = 50;
var block_height = 50;
var bombs = [];
number_of_blocks = (minefield_width * minefield_height) / (block_width * block_height);
$("#new_game").click(function() {
create_blocks();
create_bombs();
});
function random(min, max) {
return Math.floor(Math.random() * (max - min)) + min;
}
function create_blocks() {
//Create the "normal blocks".
for (var i = 0; i < number_of_blocks; i++) {
var block = document.createElement("div");
block.style.width = block_width + "px";
block.style.height = block_height + "px";
block.className = "block";
block.id = "b" + i;
block.onclick = function() {
console.log(this.id);
this.style.backgroundColor = "#ddd";
};
document.getElementById("field").appendChild(block);
}
}
function create_bombs() {
//Select a "normal block" and transform it into a "bomb block".
for (var i = 0; i < number_of_bombs; i++) {
var random_block = bombs_do_not_repeat();
var bomb = document.getElementById(random_block);
bomb.style.backgroundColor = "red";
bomb.classList.add("bomb");
bomb.onclick = function() {
alert("GAME OVER");
};
bombs[i] = random_block;
}
}
function bombs_do_not_repeat() {
//Should prevent a 'bomb block' to go inside the same 'block' more than 1 time. Example:
//CORRECT: bombs[] = "b1", "b2", "b3", "b4", "b5";
//INCORRECT: bombs[] = "b1", "b1", "b3", "b4", "b4";
var random_num = "b" + random(1, number_of_blocks);
for (var j = 0; j < bombs.length; j++) {
if (random_num == bombs[j]) {
console.info("random_num = " + random_num + " && bombs[" + j + "] = " + bombs[j]);
bombs_do_not_repeat();
}
}
return random_num;
}
* {
list-style: none;
font-family: sans-serif;
margin: 0px;
}
#field {
width: 500px;
height: 500px;
border: solid 1px black;
margin: 0px auto;
margin-top: 50px;
overflow: auto;
background-color: #ccc;
}
.block {
background-color: #aaa;
border: solid 1px #000;
box-sizing: border-box;
float: left;
cursor: pointer;
}
.block:hover {
background-color: #eee
}
.block:active {
background-color: #ddd
}
#container {
overflow: auto;
}
#menu {
width: 100%;
height: auto;
background-color: #333;
overflow: auto;
}
#menu li {
float: left;
text-align: center;
width: 100px;
color: white;
cursor: pointer;
}
#menu li:hover {
background-color: #555
}
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
</head>
<body>
<div id="container">
<div id="menu">
<ul>
<li id="new_game">New Game</li>
</ul>
</div>
<div id="field"></div>
</div>
</body>
</html>
SOLVED:
function bombs_do_not_repeat(){
//Should prevent a 'bomb block' to go inside the same 'block' more than 1 time. Example:
//CORRECT: bombs[] = "b1", "b2", "b3", "b4", "b5";
//INCORRECT: bombs[] = "b1", "b1", "b3", "b4", "b4";
var random_num = "b" + random(1,number_of_blocks);
for(var j = 0; j < bombs.length; j++){
if(random_num == bombs[j]){
console.info("random_num = " + random_num + " && bombs[" + j + "] = " + bombs[j]);
return random_num = bombs_do_not_repeat();
}
}
return random_num;
}

You're recursively calling bombs_do_not_repeat(), but always ignoring the recursive result and just going with whatever was selected first whether it's a repeat or not.
I suspect you mean to assign the result of the recursion:
random_num = bombs_do_not_repeat();

I suggest you to change your function to this
function bombs_do_not_repeat() {
var check = false;
var random_num;
do{
random_num = "b" + random(1, number_of_blocks);
for (var j = 0; j < bombs.length && !check; j++) {
if (random_num == bombs[j]) {
console.info("random_num = " + random_num + " && bombs[" + j + "] = " + bombs[j]);
check = true;
}
}
}while(check);
return random_num;
}

Instead of creating each random number prepare a random (shuffled) array. Something like this.
var number_of_blocks = 0;
var number_of_bombs = 10;
var minefield_width = 500;
var minefield_height = 500;
var block_width = 50;
var block_height = 50;
var bombs = [];
var blockArr = []; //helper array
number_of_blocks = (minefield_width * minefield_height) / (block_width * block_height);
$("#new_game").click(function() {
//reset blockArr and bombs
bombs = [];
blockArr = [];
//clean the field
document.getElementById('field').innerHTML = '';
create_blocks();
//blockArr is now fillewd
bombs = blockArr.sort(function() {
return Math.random() < 0.5 ? -1 : 1;
}) //shuffle
.slice(0, number_of_bombs);
//for debug purpose
//console.log(bombs);
create_bombs();
});
//function random(min, max) {//obsolete
// return Math.floor(Math.random() * (max - min)) + min;
//}
function create_blocks() {
//Create the "normal blocks".
for (var i = 0; i < number_of_blocks; i++) {
//fill blockArr in the samee loop
blockArr.push(i);
var block = document.createElement("div");
block.style.width = block_width + "px";
block.style.height = block_height + "px";
block.className = "block";
block.id = "b" + i;
block.onclick = function() {
console.log(this.id);
this.style.backgroundColor = "#ddd";
};
document.getElementById("field").appendChild(block);
}
}
function create_bombs() {
//Select a "normal block" and transform it into a "bomb block".
for (var i = 0; i < number_of_bombs; i++) {
//var random_block = bombs_do_not_repeat(); //no need
var bomb = document.getElementById('b' + bombs[i]); //random_block);
bomb.style.backgroundColor = "red";
bomb.classList.add("bomb");
bomb.onclick = function() {
alert("GAME OVER");
};
//bombs[i] = random_block;
}
}
/*
function bombs_do_not_repeat() { //obsolete
//Should prevent a 'bomb block' to go inside the same 'block' more than 1 time. Example:
//CORRECT: bombs[] = "b1", "b2", "b3", "b4", "b5";
//INCORRECT: bombs[] = "b1", "b1", "b3", "b4", "b4";
var random_num = "b" + random(1, number_of_blocks);
for (var j = 0; j < bombs.length; j++) {
if (random_num == bombs[j]) {
console.info("random_num = " + random_num + " && bombs[" + j + "] = " + bombs[j]);
bombs_do_not_repeat();
}
}
return random_num;
}
*/
* {
list-style: none;
font-family: sans-serif;
margin: 0px;
}
#field {
width: 500px;
height: 500px;
border: solid 1px black;
margin: 0px auto;
margin-top: 50px;
overflow: auto;
background-color: #ccc;
}
.block {
background-color: #aaa;
border: solid 1px #000;
box-sizing: border-box;
float: left;
cursor: pointer;
}
.block:hover {
background-color: #eee
}
.block:active {
background-color: #ddd
}
#container {
overflow: auto;
}
#menu {
width: 100%;
height: auto;
background-color: #333;
overflow: auto;
}
#menu li {
float: left;
text-align: center;
width: 100px;
color: white;
cursor: pointer;
}
#menu li:hover {
background-color: #555
}
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
</head>
<body>
<div id="container">
<div id="menu">
<ul>
<li id="new_game">New Game</li>
</ul>
</div>
<div id="field"></div>
</div>
</body>
</html>

Why does my code not work in Safari or Opera?

There is a function in js which displays messages to the table (messages are stored in json). In Google Chrome, it works, but Safari, Opera or Microsoft Edge - no!
There is a mistake in code which is associated with the call to setTimeout (callback, 5000)(nothing is sent to the callback).So, For (var i = 0; i <respond.length; i ++) will not work since respond === undefined.
But why is it so?
callback(
[{
"time": "1500303264",
"user": "qwe",
"message": "we",
"id": 1
},
{
"time": "1500303987",
"user": "Max",
"message": "q",
"id": 2
}
]);
function smile(mess) {
var smile = ":)";
var graficSmile = "<img src = './image/Smile.png' alt='Smile' align='middle'>";
var string_with_replaced_smile = mess.replace(smile, graficSmile);
var sad = ":("
var graficSad = "<img src = './image/Sad.png' alt='Smile' align='middle'>";
var string_with_replaced_smile_and_sad = string_with_replaced_smile.replace(sad, graficSad);
return string_with_replaced_smile_and_sad;
}
$.getJSON('data/messages.json', callback);
var exists = [];
function callback(respond) {
var timeNow = Date.now();
for (var i = 0; i < respond.length; i++) {
var data = respond[i];
if (exists.indexOf(data.id) != -1) continue;
var timeInMessage = data.time * 1000;
var diff_time = (timeNow - timeInMessage);
if (diff_time <= 3600000) {
var rowClone = $('.mess_hide').clone().removeClass('mess_hide');
var newDate = new Date(timeInMessage);
var dateArray = [newDate.getHours(), newDate.getMinutes(), newDate.getSeconds()]
var res = dateArray.map(function(x) {
return x < 10 ? "0" + x : x;
}).join(":");
$('#messages').append(rowClone);
$('.time', rowClone).html(res);
$('.name', rowClone).html(data.user);
$('.message', rowClone).html(smile(data.message));
$('.scroller').scrollTop($('#messages').height());
exists.push(data.id);
}
}
setTimeout(function(){callback(respond)}, 5000);
}
.scroller {
width: 490px;
height: 255px;
max-height: 255px;
overflow-y: auto;
overflow-x: hidden;
}
table#messages {
min-height: 260px;
width: 100%;
background: #fffecd;
border: none;
}
table#messages::-webkit-scrollbar {
width: 1em;
}
table#messages::-webkit-scrollbar-track {
-webkit-box-shadow: inset 0 0 6px rgba(0, 0, 0, 0.3);
}
table#messages::-webkit-scrollbar-thumb {
background-color: darkgrey;
outline: 1px solid slategrey;
}
tr {
height: 20%;
display: block;
}
td.time,
td.name {
width: 70px;
max-width: 75px;
text-align: center;
}
td.name {
font-weight: bold;
}
form#text_submit {
display: inline-flex;
align-items: flex-start;
}
input#text {
width: 370px;
height: 30px;
margin-top: 20px;
background: #fffecd;
font-family: 'Montserrat';
font-size: 16px;
border: none;
align-self: flex-start;
}
input#submit {
padding: 0;
margin-left: 21px;
margin-top: 21px;
height: 30px;
width: 95px;
background: #635960;
border: none;
color: white;
font-family: 'Montserrat';
font-size: 16px;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="scroller">
<table id="messages">
<tr class="mess_hide">
<td class="time"></td>
<td class="name"></td>
<td class="message"></td>
</tr>
</table>
</div>
<form method="POST" id="easyForm">
<input type="text" name="text" id="text">
<input type="submit" value="Send" id="submit">
</form>
</div>
Chrome
Opera

Since it is assumed that the var exists - array, but the value of the array ([]) is assigned to it only later, after the call $.getJSON(...). So, when callback is called for the first time value [] is not set for exists.We just need to move var exists above the first call of callback.
When callback is called by the timer, nothing is passed to it. But timer needs to reread the messages from the file and display them on the screen.So, instead setTimeout(function(){callback(respond)}, 5000); we need setTimeout(function(){$.getJSON('data/messages.json', callback);}, 5000);.
var exists = [];
$.getJSON('data/messages.json', callback);
function callback(respond) {
var timeNow = Date.now();
for (var i = 0; i < respond.length; i++) {
var data = respond[i];
if (exists.indexOf(data.id) != -1) continue;
var timeInMessage = data.time * 1000;
var diff_time = (timeNow - timeInMessage);
if (diff_time <= 3600000) {
var rowClone = $('.mess_hide').clone().removeClass('mess_hide');
var newDate = new Date(timeInMessage);
var dateArray = [newDate.getHours(), newDate.getMinutes(), newDate.getSeconds()]
var res = dateArray.map(function(x) {
return x < 10 ? "0" + x : x;
}).join(":");
$('#messages').append(rowClone);
$('.time', rowClone).html(res);
$('.name', rowClone).html(data.user);
$('.message', rowClone).html(smile(data.message));
$('.scroller').scrollTop($('#messages').height());
exists.push(data.id);
}
}
setTimeout(function() {
$.getJSON('data/messages.json', callback);
}, 5000);
}

Since callback requires an array to be passed as an argument, setTimeout must ensure that when it calls callback, it passes the array.
Change
setTimeout(callback, 5000);
to
setTimeout(function(){callback(respond)}, 5000);
which allows callback to be called with an argument as the body of an anonymous function that will be called by setTimeout.
Also, as a side note, if you used respond.forEach() instead of a counting for loop, the code would be much cleaner:
respond.forEach(function(data) {
if (exists.indexOf(data.id) != -1) continue;
var timeInMessage = data.time * 1000;
var diff_time = (timeNow - timeInMessage);
if (diff_time <= 3600000) {
var rowClone = $('.mess_hide').clone().removeClass('mess_hide');
var newDate = new Date(timeInMessage);
var dateArray = [newDate.getHours(), newDate.getMinutes(), newDate.getSeconds()]
var res = dateArray.map(function(x) {
return x < 10 ? "0" + x : x;
}).join(":");
$('#messages').append(rowClone);
$('.time', rowClone).html(res);
$('.name', rowClone).html(data.user);
$('.message', rowClone).html(smile(data.message));
$('.scroller').scrollTop($('#messages').height());
exists.push(data.id);
}
});

Textarea Count Lines, Count hyphenated Lines using regular expression

I have been trying to figure out the issue with using regular expressions to ignore lines starting with double hyphens and count the single lines as separate and double hyphenated lines counted as separately and display outside the text area.
I have tried and got success with counting the each line but ignoring hyphens and counting I have no idea on how can I do that using regular expressions.
On another side, I want to append the code inside of a span Item buts it's removing the text of item element.
Here is my code and sample Image.
$(document).ready(function(){
var items = $('#items');
var groups = $('#groups');
$('#ingredients_list').keydown(function(e) {
newLines = $(this).val().split("\n").length;
items.text(newLines);
});
});
.ingredients__section {
padding: 20px;
width: 100%;
box-sizing: border-box;
}
.ingredients__section textarea {
width: 100%;
}
.ingredients__section h2 {
color:#0433a7;
margin-bottom: 20px;
}
.ingredients__header {
display: table;
width: 100%;
table-layout:fixed;
}
.ingredients__title { display: table-cell; }
.ingredients__countinfo { display: table-cell; text-align:right; }
.item-count,
.group-count { padding: 5px 15px; background-color:#e4ebef; margin-left: 5px; font-size: 14px; }
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="ingredients__section">
<div class="ingredients__header">
<div class="ingredients__title"><h2>INGREDIENTS</h2></div>
<div class="ingredients__countinfo">
<span class="group-count" id="groups">Groups:</span>
<span class="item-count" id="items">Items:</span>
</div>
</div>
<form>
<textarea id="ingredients_list" rows="15"></textarea><br />
</form>
</div>

Initialize counters
var groupsCount = 0;
var itemsCount = 0;
Get array of entered text
var arrayOfItems = $(this).val().split("\n");
Run for all elements in array and check first two symbols. If it is -- then groupsCount++ else itemsCount++
for (var i=0; i<arrayOfItems.length; i++) {
if (arrayOfItems[i][0] === '-' && arrayOfItems[i][1] === '-') {
groupsCount += 1;
itemsCount -= 1;
groups.text("Groups: " + groupsCount);
} else {
itemsCount += 1;
items.text("Items: " + itemsCount);
}
}
$(document).ready(function(){
var items = $('#items');
var groups = $('#groups');
$('#ingredients_list').keypress(function(e) {
var groupsCount = 0;
var itemsCount = 0;
var arrayOfItems = $(this).val().split("\n");
for (var i=0; i<arrayOfItems.length; i++) {
if (arrayOfItems[i] != '') {
if (arrayOfItems[i][0] === '-' && arrayOfItems[i][1] === '-') {
groupsCount += 1;
groups.text("Groups: " + groupsCount);
} else {
itemsCount += 1;
items.text("Items: " + itemsCount);
}
} else {
groups.text("Groups: " + groupsCount);
items.text("Items: " + itemsCount);
}
}
});
$(document).mousedown(function (e) {
var groupsCount = 0;
var itemsCount = 0;
var arrayOfItems = $('#ingredients_list').val().split("\n");
for (var i=0; i<arrayOfItems.length; i++) {
if (arrayOfItems[i] != '') {
if (arrayOfItems[i][0] === '-' && arrayOfItems[i][1] === '-') {
groupsCount += 1;
groups.text("Groups: " + groupsCount);
} else {
itemsCount += 1;
items.text("Items: " + itemsCount);
}
} else {
groups.text("Groups: " + groupsCount);
items.text("Items: " + itemsCount);
}
}
});
});
.ingredients__section {
padding: 20px;
width: 100%;
box-sizing: border-box;
}
.ingredients__section textarea {
width: 100%;
}
.ingredients__section h2 {
color:#0433a7;
margin-bottom: 20px;
}
.ingredients__header {
display: table;
width: 100%;
table-layout:fixed;
}
.ingredients__title { display: table-cell; }
.ingredients__countinfo { display: table-cell; text-align:right; }
.item-count,
.group-count { padding: 5px 15px; background-color:#e4ebef; margin-left: 5px; font-size: 14px; }
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="ingredients__section">
<div class="ingredients__header">
<div class="ingredients__title"><h2>INGREDIENTS</h2></div>
<div class="ingredients__countinfo">
<span class="group-count" id="groups">Groups:</span>
<span class="item-count" id="items">Items:</span>
</div>
</div>
<form>
<textarea id="ingredients_list" rows="15"></textarea><br />
</form>
</div>

Its good, But I have seen that if you type a word with double hyphens -- or without the same --, it is adding +1 to both groupItems and listItems which are not what you are looking for.
It means if you start group name with -- it should add +1 to groups instead of items, so here is the small change in your code that might help you to fix.
$(document).ready(function(){
var items = $('#items');
var groups = $('#groups');
$('#ingredients_list').keypress(function(e) {
var groupsCount = 0;
var itemsCount = 0;
var arrayOfItems = $(this).val().split("\n");
console.log(arrayOfItems);
for (var i=0; i<arrayOfItems.length; i++) {
if (arrayOfItems[i][0] === '-' && arrayOfItems[i][1] === '-') {
groupsCount += 1;
groups.text("Groups: " + groupsCount);
} if (arrayOfItems[i][0] === '.'){ // I have given '.' here in single quote, you can add regex what you are looking for like numbers, letters, or expressions that start with.
itemsCount += 1;
items.text("Items: " + itemsCount);
}
}
});
});

Simple JavaScript chess board

Could anyone give me a hint on how to generate a chess board (8x8) using JavaScript, using a table tags or ?
I've got the following so far:
<DOCTYPE html>
<html>
<head>
<style>
div
{
border:1px solid black;
width:20px;
height:20px;
}
</style>
</head>
<body>
<script type="text/javascript">
// create a chess table 8x8.
var count = 0;
while (count < 64)
{
if (count % 2 == 0)
{
if (count % 8 == 0 && count !=0)
{
document.write('<br/><div style="background-color:#000000;float:left;">&nbsp</div>');
}
else
{
document.write('<div style="background-color:#000000;float:left;">&nbsp</div>');
}
}
else
{
document.write('<div style="background-color:#FFFFFF;float:left;">&nbsp</div>');
}
/*
*/
count++;
}
</script>
</body>
</html>
I tried to assign black and white to each odd and even number respectively, but it doesn't work this way.
Thank you in advance.

I can not test it at this moment but this should work. This code creates a 8x8 table in which black cells are tagged with "black" class and white cells are tagged with "white" class. Use CSS to give them color. I hope it helps.
var table = document.createElement("table");
for (var i = 1; i < 9; i++) {
var tr = document.createElement('tr');
for (var j = 1; j < 9; j++) {
var td = document.createElement('td');
if (i%2 == j%2) {
td.className = "white";
} else {
td.className = "black";
}
tr.appendChild(td);
}
table.appendChild(tr);
}
document.body.appendChild(table);

At some point for me, this became code golf:
http://jsfiddle.net/4Ap4M/
JS:
for (var i=0; i< 64; i++){
document.getElementById("mainChessBoard").appendChild(document.createElement("div")).style.backgroundColor = parseInt((i / 8) + i) % 2 == 0 ? '#ababab' : 'white';
}
HTML:
<div id="mainChessBoard">
</div>
CSS:
#mainChessBoard
{
width:160px;
height:160px;
border:1px solid black;
}
div
{
width:20px;
height:20px;
float:left;
}

This is the basic foundation to build your chess board.
You can check out the chess board pattern in the console.
var chessBoard = function(size){
var hash = '#'
var space = '_'
for (var i = 0; i < size; i++)
{
hash += '\n'
for (var j = 0; j < size; j++)
{
if((i +j) % 2 == 0)
{
hash += space
}
else
{
hash += "#"
}
};
};
console.log(hash)
}(8)

You can generate boards of any size you want, and this way is pretty easy to change the size of the squares and the colors. you don't need to change anything else.
It is good practice to keep appearance on the stylesheet.
Also don't use document.write
http://jsfiddle.net/YEJ9A/1/
Javascript
var x=8;
var y=8;
var chessBoard = document.getElementById("chessBoard");
for (var i=0; i<y; i++){
var row = chessBoard.appendChild(document.createElement("div"));
for (var j=0; j<x; j++){
row.appendChild(document.createElement("span"));
}
}
CSS
#chessBoard span{
display: inline-block;
width: 32px;
height: 32px;
}
#chessBoard div:nth-child(odd) span:nth-child(even),
#chessBoard div:nth-child(even) span:nth-child(odd){
background-color: black;
}
#chessBoard div:nth-child(even) span:nth-child(even),
#chessBoard div:nth-child(odd) span:nth-child(odd){
background-color: silver;
}

May be you want to do it with divs, not with the table. So here is the solution for it.
$(document).ready(function() {
for (var i = 1; i <= 8; i++) {
var divRow = $("<div>", {
class: "row",
});
for (var j = 1; j <= 8; j++) {
var div = $("<div>", {
class: "square"
});
if (i % 2 == j % 2) {
$(div).addClass("white");
} else {
$(div).addClass("black");
}
divRow.append(div);
}
$("#board").append(divRow);
}
});
#board {
margin: 0;
width: 256px;
height: 256px;
border: solid 1px #333;
}
#board .row {
margin: 0;
}
.square {
height: 32px;
width: 32px;
background: #efefef;
float: left;
}
.square.white {
background: #fff;
}
.square.black {
background: #333;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.0/jquery.min.js"></script>
<div id="board"></div>

A little modernization, using css variables, css attr() and dataset attributes.
This allows to tweak themes, and keep stuffs simple.
const cols = {0:"A", 1:"B", 2:"C", 3:"D", 4:"E", 5:"F", 6:"G", 7:"H"}
const table = document.createElement("table");
table.className = "board";
for (let i = 1; i < 9; i++) {
let tr = document.createElement('tr');
tr.dataset.line = i
for (let j = 1; j < 9; j++) {
let td = document.createElement('td');
td.dataset.col = cols[j-1];
td.dataset.line = i;
td.className = (i%2 === j%2) ? "white square" : "black square";
tr.appendChild(td);
}
table.appendChild(tr);
}
document.querySelector("div").appendChild(table);
:root {
--size: 640px;
--backcolor: darkslategray;
--dark: grey;
--light: white;
--legend: azure;
--hover: lightgreen
}
.board {
width: var(--size);
height: var(--size);
border: 32px solid;
border-color: var(--backcolor);
border-radius: 0.2rem;
}
.square {
border: 1px black solid;
}
.white{
background: var(--light);
}
.black{
background: var(--dark)
}
.board tr::before {
content: attr(data-line);
position: absolute;
margin: 1.8rem 0 0rem -1.5rem;
font-size: larger;
color: var(--legend);
}
.board tr::after {
content: attr(data-line);
position: absolute;
margin: 1.8rem 0 0rem 0.8rem;
font-size: larger;
color: var(--legend);
}
.board tr:first-child > td::before {
content: attr(data-col);
position: absolute;
margin: -4rem 0 0rem 1.6rem;
font-size: larger;
color: var(--legend);
}
.board tr:last-child > td::after {
content: attr(data-col);
position: absolute;
margin: 2.6rem 0 0rem 1.6rem;
font-size: larger;
color: var(--legend);
}
td:hover {
background: var(--hover);
cursor: pointer
}
<div></div>

The following code will print chess board using only HTML and JavaScript.
<script>
document.write("<table border='1' width='200' height='200'>");
for(var i=1; i<=8; i++)
{
document.write("<tr>");
for(var j=1; j<=8; j++)
{
if((i+j)%2!=0)
{
document.write("<td bgcolor='white'></td>");
}
else
{
document.write("<td bgcolor='black'></td>");
}
}
document.write("</tr>");
}
document.write("</table>");
</script>

You should try this one this will really work
<DOCTYPE html>
<html>
<head>
<style>
.chessBoard {
display: inline-block;
border: 2px solid lightGray;
}
.chessBoard div {
line-height: 1px;
}
.chessBoard span {
display: inline-block;
width: 32px;
height: 32px;
background-color: snow;
}
</style>
</head>
<body>
<div class="chessBoard" id="chessBoardNormal"></div>
<div class="chessBoard" id="chessBoardRandom"></div>
<script>
function colorNormal(x, y, color) {
var chessBoard = document.getElementById("chessBoardNormal");
for (var i = 0; i < x; i++) {
var row = chessBoard.appendChild(document.createElement("div"));
for (var j = 0; j < y; j++) {
var span = document.createElement('span');
if (i & 1) { // odd
if (j & 1) { // white
} else { // black
span.style.backgroundColor = color;
}
} else { // even
if (j & 1) { // black
span.style.backgroundColor = color;
}
}
row.appendChild(span);
}
}
}
function colorRandom(x, y) {
colorNormal(8, 8, Math.random() > .5 ? 'black' : '#CFD65C');
}
function getRandomHexColor() {
return '#' + Math.floor(Math.random() * 16777215).toString(16);
}
colorNormal(8, 8, 'black');
</script>
</body>
</html>

My idea is simple, if row is even then start with white piece otherwise start with black piece.
HTML:
<div id="mainChessBoard"></div>
Javascript:
const fragment = document.createDocumentFragment();
const board = document.getElementById("mainChessBoard");
const size = 8;
for (let i = 0; i < size; i++) {
let start = i % 2 === 0 ? 0 : 1; // if row is even then start with white otherwise start with black;
for (let j = 0; j < size; j++) {
const div = document.createElement('div');
div.classList.add(start === 1 ? "black" : "white");
fragment.appendChild(div);
start = start === 1 ? 0 : 1;
}
}
board.appendChild(fragment);

Here's a plain JS copy-paste solution. I know it's not that clean in terms of conditioning but it does the job comprehensibly and it's quite straight forward. Field size is easily adjustable as well.
const fieldSize = 50;
const whiteField = document.createElement("div");
whiteField.style = `height:${fieldSize}px;width:${fieldSize}px;background-color:white;display:inline-block`;
const blackField = document.createElement("div");
blackField.style = `height:${fieldSize}px;width:${fieldSize}px;background-color:black;display:inline-block`;
for (let i = 0; i < 8; i++) {
for (let j = 0; j < 8; j++)
i % 2 === 0 ?
j % 2 === 0 ?
document.body.appendChild(blackField.cloneNode(true)) :
document.body.appendChild(whiteField.cloneNode(true)) :
j % 2 === 0 ?
document.body.appendChild(whiteField.cloneNode(true)) :
document.body.appendChild(blackField.cloneNode(true));
document.body.appendChild(document.createElement("br"));
}

We can always think of a better performance, here's the DOM optimized solution using documentFragments -
// main container
let container = document.querySelector("#main");
// a fragment object to store a 2-D mesh of rows and columns
let fragment = new DocumentFragment();
for (let i = 0; i < 8; i++) {
// a fragment object to store a single row with 8 columns
let rowFragment = new DocumentFragment();
for (let j = 0; j < 8; j++) {
// div element for a column
let col = document.createElement("div");
col.style.border = "1px solid";
if ((i + j) % 2 == 0) col.style.background = "black";
else col.style.background = "white";
// adding column in a document fragment
rowFragment.appendChild(col);
}
// adding row in a main fragment
fragment.appendChild(rowFragment);
}
// adding fragment to a DOM one time - this will update the DOM only once
container.appendChild(fragment);
.container {
display: flex;
width: 416px; /* width + horizontal border of each cell ((50 + 2) * 8) */
height: 416px; /* height + vertical border of each cell ((50 + 2) * 8) */
}
div {
flex-wrap: wrap; /* to fit 8 cells in a row as per the width */
width: 50px;
height: 50px;
}
<div class="container" id="main"></div>
Here, the DocumentFragment creates an object of elements we add, but it isn't a part of the active document tree unless we append it to any other DOM node.

Javascript:
var i, j, clas;
for (i = 0; i < 8; i++) {
for (j = 0; j < 8; j++) {
clas = '';
if (j === 0) clas = 'first ';
else if (j === 7) clas = 'last ';
clas += (i % 2 == j % 2) ? 'white' : 'black';
var field = document.createElement('div');
field.className = clas;
document.body.appendChild(field);
}
}
CSS:
div {
float: left;
width: 20px;
height: 20px;
}
.first {
clear: left;
}
.black {
background: black;
}
.white {
background: red;
}
Sample: http://jsfiddle.net/YJnXG/2/

You mean like this?
.... html.....
<table>
<tr>
<script language='javascript'>
<!--
alternate();
//-->
</script>
</tr>
</table>
....more html.....
function alternate()
{
var numOfCells = 6;
var num = 0;
for (i = 0; i < numOfCells ; i++)
{
txt = "<td bgColor='";
txt += (num % 2 == 0) ? 'red' : 'black';
txt += "'>"
document.write(txt);
num++;
}
}
The % sign is mod; it returns the remainder of a division. the "(...) ? ... : ...;" construction is like an if/else. If the condition is true, the first option -- else the second.