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Counting up and then back down in a for loop javascript

Function oddNumbers(){
Var odds ="";
For(index=0; index <=10; index ++){
If(index%2 !=0){odds+=index +"."}
}
}
OddNumbers();
Trying to count all odd counting numbers up then back down again in a for loop. I can get it to go up with the code again. But when I try nested for I cannot get it to go back down again in the same loop.
How would I get it to loop up then back down?

Assuming you want to use only one loop definition, you have to define custom conditionExpression and incrementExpression.
Here is a quick example.
var direction = 1;
//REM: What gets added on each iteration?
function incrementExpression(){
//REM: Increase or decrease depending on direction
return 1*direction
}
//REM: What gets evaluated on each iteration?
function conditionExpression(i){
if(i < 10 && direction === 1){
return true
}
if(i === 10 && direction === 1){
direction = -1
return true
}
if(i >= 0 && direction === -1){
direction = -1
return true
};
//REM: Returns false if direction downwards and i lower zero
return false
}
for(var i=0; conditionExpression(i); i+=incrementExpression(i)){
console.log(i)
}

You can reverse your for loop on your use-case. See code snippet below:
function oddNumbers() {
var odds = "";
for(index=0; index <=10; index ++){
if(index%2 !=0) {
odds+=index +"."
console.log(odds);
}
}
for(index = 10; index > 0; index--) {
if(index % 2 != 0) {
odds+=index +"."
console.log(odds);
}
}
}
oddNumbers();
Im not sure if that's what you want but that's what I understand on your given code on your question.

Having issues trying to solve N Rook problem . Always get n*n solution and not N factorial

I'm trying to get N ways of solves a N rook problem. The issue I am having is currently, I seem to get n*n solutions while it needs to be N! . Below is my code, I have written it in simple loops and functions, so it's quite long. Any help would be greatly appreciated
Note: Please ignore case for n = 2. I get some duplicates which I thought I would handle via JSON.stringify
var createMatrix = function (n) {
var newMatrix = new Array(n);
// build matrix
for (var i = 0; i < n; i++) {
newMatrix[i] = new Array(n);
}
for (var i = 0; i < n; i++) {
for (var j = 0; j < n; j++) {
newMatrix[i][j] = 0;
}
}
return newMatrix;
};
var newMatrix = createMatrix(n);
// based on rook position, greying out function
var collision = function (i, j) {
var col = i;
var row = j;
while (col < n) {
// set the row (i) to all 'a'
col++;
if (col < n) {
if (newMatrix[col][j] !== 1) {
newMatrix[col][j] = 'x';
}
}
}
while (row < n) {
// set columns (j) to all 'a'
row++;
if (row < n) {
if (newMatrix[i][row] !== 1) {
newMatrix[i][row] = 'x';
}
}
}
if (i > 0) {
col = i;
while (col !== 0) {
col--;
if (newMatrix[col][j] !== 1) {
newMatrix[col][j] = 'x';
}
}
}
if (j > 0) {
row = j;
while (row !== 0) {
row--;
if (newMatrix[i][row] !== 1) {
newMatrix[i][row] = 'x';
}
}
}
};
// checks position with 0 and sets it with Rook
var emptyPositionChecker = function (matrix) {
for (var i = 0; i < matrix.length; i++) {
for (var j = 0; j < matrix.length; j++) {
if (matrix[i][j] === 0) {
matrix[i][j] = 1;
collision(i, j);
return true;
}
}
}
return false;
};
// loop for every position on the board
loop1:
for (var i = 0; i < newMatrix.length; i++) {
var row = newMatrix[i];
for (var j = 0; j < newMatrix.length; j++) {
// pick a position for rook
newMatrix[i][j] = 1;
// grey out collison zones due to the above position
collision(i, j);
var hasEmpty = true;
while (hasEmpty) {
//call empty position checker
if (emptyPositionChecker(newMatrix)) {
continue;
} else {
//else we found a complete matrix, break
hasEmpty = false;
solutionCount++;
// reinitiaze new array to start all over
newMatrix = createMatrix(n);
break;
}
}
}
}

There seem to be two underlying problems.
The first is that several copies of the same position are being found.
If we consider the case of N=3 and we visualise the positions by making the first rook placed red, the second placed green and the third to be placed blue, we get these three boards:
They are identical positions but will count as 3 separate ones in the given Javascript.
For a 3x3 board there are also 2 other positions which have duplicates. The gets the count of unique positions to 9 - 2 - 1 -1 = 5. But we are expecting N! = 6 positions.
This brings us to the second problem which is that some positions are missed. In the case of N=3 this occurs once when i===j==1 - ie the mid point of the board.
This position is reached:
This position is not reached:
So now we have the number of positions that should be found as 9 - 2 - 1 - 1 +1;
There appears to be nothing wrong with the actual Javascript in as much as it is implementing the given algorithm. What is wrong is the algorithm which is both finding and counting duplicates and is missing some positions.
A common way of solving the N Rooks problem is to use a recursive method rather than an iterative one, and indeed iteration might very soon get totally out of hand if it's trying to evaluate every single position on a board of any size.
This question is probably best taken up on one of the other stackexchange sites where algorithms are discussed.

Having trouble displaying results correctly after changing the value of an Ace from 11 to 1 in a blackjack simulation

This is the first time I've written anything beyond a few simple lines in javascript. I know similar questions have been asked before because I've looked at a lot of them. I still can't seem to figure out what I'm doing wrong though. I am attempting to make a blackjack game simulation. I've almost got it except I keep running into problems when I need to change the value of an ace from 11 to 1. When I need to change the value of an ace from 11 to 1, it seems to only display the last player's results. Here's the script in it's entirety:
function cardShuffle(min, max) {
min = Math.ceil(min);
max = Math.floor(max);
return Math.floor(Math.random() * (max - min + 1)) + min;
}
function add(a, b) {
return a + b;
}
function contains(arr, obj) {
var i = 0;
for (;i < arr.length;i++) {
if (arr[i] === obj) {
return true;
}
}
return false;
}
function blackjack() {
var spades = "\u2660";
var clubs = "\u2663";
var hearts = "\u2665";
var diamonds = "\u2666";
var dealer = "Dealer";
var player = "Player";
var table = [player, dealer];
var suits = [hearts, clubs, diamonds, spades];
var deck = [];
// create a deck of cards
x = 0;
for (;x < suits.length; x++) {
var cards = ["A", 2, 3, 4, 5, 6, 7, 8, 9, 10, "J", "Q", "K"];
i = 0;
for (;i < cards.length; i++) {
deck.push(cards[i] + suits[x]);
}
}
i = 0;
for (;i < table.length; i++) {
var players = table[i];
var cardsToDeal = 1;
var cardsHeld = [];
var sum = [];
aces = [];
var result;
for (;0 < cardsToDeal;) {
// get a random card from the deck
var index = cardShuffle(0, deck.length - 1);
var card = deck[index];
// give the card to the player
cardsHeld.push(card);
// remove the card from the deck
deck.splice(index, 1);
// strip the suit from the card and get the value
var value = card.substring(0, card.length - 1);
if (value == "J" || (value == "Q" || value == "K")) {
value = 10;
} else {
if (value == "A") {
value = 11;
// put aces into a separate array
aces.push(value);
} else {
value = Number(value);
}
}
// put the value of the card into the sum array
sum.push(value);
// store the sum of the value in the total variable
var total = sum.reduce(add, 0);
/*
This is where I think the problem is.
It works if the last player's hand is greater than 21 and contains an ace.
But if the first players hand has an ace and is greater than 21
only those result are shown in console.log. I don't know why.
*/
if (total > 21 && contains(sum, 11)) {
var i = sum.indexOf(11);
if (i !== -1) {
sum[i] = 1;
}
total = sum.reduce(add, 0);
}
if (total >= 17 && total <= 21) {
result = Number(total);
}
if (total >= 17) {
cardsToDeal--;
}
}
console.log(players, cardsHeld, sum, total);
}
}
blackjack();

On this line:
for (;i < table.length; i++) {
... you use a variable i for a loop. But inside this loop, you redefine that variable, and change its value:
var i = sum.indexOf(11);
which results in this kind of behavior:
If you just change that variable's name to something else, it seems to work fine:
if (total > 21 && contains(sum, 11)) {
var index = sum.indexOf(11);
if (index !== -1) {
sum[index] = 1;
}
total = sum.reduce(add, 0);
}
Be careful about variable scopes when using the var keyword, they are not limited to blocks -unlike let- but to functions (and be sure to add a var in front of the first definition, to avoid making it global). Also, just a piece of advice. for loops are generally used when you know how many iterations you're going to do. This:
for (;0 < cardsToDeal;) { /*...*/ }
would be better with a while loop.

When you check for Aces, you declare i again. This changes the value of i in your table loop. Change the the second var i to var ii and you should be good. To better understand this, you can look up more about Javascript scope.
if (total > 21 && contains(sum, 11)) {
var ii = sum.indexOf(11); // This is what changed
if (ii !== -1) {
sum[ii] = 1;
}
total = sum.reduce(add, 0);
}

don't let adverts appear near each other jquery

Here is my DEMO
jQuery(document).ready(function(){
var insertionTemplate = jQuery(".hiddenAdBox").eq(0).html(),
insertionTarget = jQuery('ul'),
insertionTargetChildren = insertionTarget.find('li'),
insertionFrequency = 2;
var random;
for (var i = 0; i < insertionFrequency; i++) {
random = Math.floor(Math.random() * insertionTargetChildren.length) + 0;
insertionTargetChildren.eq(random).after(insertionTemplate);
}
});
I have list of items, also need to show ads randomly when you refresh page. Now when ads count is 2 (insertionFrequency = 2) there is a time when they appear near each other but it shouldn't be so. How can I detect it and don't let ads appear near each other?
Attaching screenshots:

To prevent ads horizontally you can do it as below:
for (var i = 0; i < insertionFrequency; i++) {
random = Math.floor(Math.random() * insertionTargetChildren.length) + 0;
if(insertionTargetChildren.eq(random).next('.placeforad').length || insertionTargetChildren.eq(random).prev('.placeforad').length)
//check whether its previous li or next li has ad with class .placeforad
{
i--; //decrease the count so as to come up with separate random number
}
else
insertionTargetChildren.eq(random).after(insertionTemplate);
}
DEMO
But for vertical prevention since you do not have equal amount of squares in each row like 1st and 2nd rows have 3 blocks and last row has only 2, its very tricky to identify horizontal. If there equal amount of squares then some approach might be taken to achieve that too..
Update
Since you agreed to get 3 blocks in a row the below code will avoid getting ads horizontally as well as vertically
A small DEMO
for (var i = 0; i < insertionFrequency; i++) {
random = Math.floor(Math.random() * insertionTargetChildren.length) + 0;
var currentElement=insertionTargetChildren.eq(random);
var addedElement=$('li.placeforad:visible');
if(currentElement.next('.placeforad').length || currentElement.prev('.placeforad').length)
{
i--;
}
else
{
if(i!=0)
{
if(addedElement.index() > currentElement.index() &&
(addedElement.index() - currentElement.index())==3)
{
i--;
}
else if(currentElement.index() - (addedElement.index()-1)==3)
{
i--;
}
else
{
insertionTargetChildren.eq(random).after(insertionTemplate);
}
}
else
insertionTargetChildren.eq(random).after(insertionTemplate);
}
}

Javascript Smallest Multiple Keeps Crashing

I am currently going through project euler trying to get better at javascript. I am stuck on one problem that i can't seem to figure out.
The question is:
2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder. What is the smallest positive number that is evenly divisible by all of the numbers from 1 to 20?
So I searched stack and found a few similar topics when i got stuck but everyones code seems to be a bit more complex than what I came up with. My problem is i was able to create the correct program to find the smallest multiple from 1-10 which i was able to get 2520 with.
However, when i adjust my program to work for numbers 1-20 it crashes. I can get 1-19 but once i do 20 i keep crashing. Here is my code. If you change it to count != 10 and i <= 10 you can get the answer 2520 but 20 just doesn't seem to work. Any help would be appreciated.
<script>
var num = 0;
var count = 0;
while (count != 20) {
num++;
count = 0;
for (var i = 1; i <= 20; i++) {
if (num % i == 0) {
count++;
}
}
}
console.log(num);
console.log(count);
</script>

It doesn't crash, just takes long time, since your script is inefficient.
<script>
var num = 0;
var count = 0;
var numbers=20;
while (count != numbers) {
num+=numbers;
count = 0;
for (var i = 1; i <= numbers; i++) {
if (num % i == 0) {
count++;
}
else {break;}
}
}
console.log(num);
console.log(count);
</script>

Yeah, not breaking, just taking a REALLY long time. This should be a much more efficient approach:
var num = 1;
var isDivisible = false;
var startTime = (new Date().getTime());
while (!isDivisible) {
for (var i = 20; i > 1; i--) {
if (num % i !== 0) {
isDivisible = false;
num = num + (i + 1);
break;
}
else {
isDivisible = true;
}
}
}
console.log(num);
console.log("Finished in " + (((new Date().getTime()) - startTime) / 1000) + " seconds");
Results:
232792560
Finished in 0.166 seconds
Note: above results from JSFiddle . . . finished in 26.57 seconds in Firebug. :)