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DOM assign an id to child Javascript

I have created a grid with div, class and id. I want to randomly create a yellow square and I want to assign an id= 'yellowSquare' how do I do it?
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 playerOne = [];
while (playerOne.length < 1) {
var randomIndex = parseInt(99 * Math.random());
if (playerOne.indexOf(randomIndex) === -1) {
playerOne.push(randomIndex);
var drawPone = document.getElementById('square' + randomIndex);
drawPone.style.backgroundColor = 'yellow';
}
}
#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;
}
<div id="grid-box"></div>
I am new to Javascript / jQuery. Any help will be much appreciated ! Thank you

There are two options to your question. You can either change the id of the yellow square which is already created from your code, or create a child element within the square, which looks the same as your current solution. Creating a new child element will let you keep the numeric id pattern for the grid:
Changing the ID :
var element = document.getElementById('square' + randomIndex)
element.id = "yellowSquare";
Adding new element inside:
var node = document.createElement("DIV");
node.id = "yellowSquare";
node.style = "background-color:yellow;height:100%;width:100%;";
var element = document.getElementById('square' + randomIndex)
element.appendChild(node);
I set the styling of the div child to 100% width and height, as it has no content, and would get 0 values if nothing was specified. This should make it fill the parent container.
There are also multiple other ways to achieve the same result, for instance with JQuery.

Use the HTMLElement method setAttribute (source);
...
var drawPone = document.getElementById('square' + randomIndex);
drawPone.style.backgroundColor = 'yellow';
drawPone.setAttribute('id', 'yellowSquare');
...

As you requested in your comment how to move the square i made an example how you can move it left and right using jQuery next() and prev() functions. However because your html elements are 1 dimensional it's not easy to move them up/down and check the sides for collisions. Better would be to create your html table like with rows and columns and this way create a 2 dimensional play field.
Also added a yellowSquery class for selection with $drawPone.addClass('yellowSquare');.
Also since you like to use jQuery I changed your existing code to jQuery function. Might help you learn the framework.
var $grid = $("#grid-box");
for (var i = 1; i <= 100; i++) {
var $square = $("<div>");
$square.addClass('square');
$square.attr('id','square' + i);
$grid.append($square);
}
var playerOne = [];
while (playerOne.length < 1) {
var randomIndex = parseInt(99 * Math.random());
if (playerOne.indexOf(randomIndex) === -1) {
playerOne.push(randomIndex);
var $drawPone = $('#square' + randomIndex);
$drawPone.addClass('yellowSquare');
}
}
$('#button_right').on('click', function(){
$yellowSquare = $('.yellowSquare')
$yellowSquareNext = $yellowSquare.next();
$yellowSquare.removeClass('yellowSquare');
$yellowSquareNext.addClass('yellowSquare');
});
$('#button_left').on('click', function(){
$yellowSquare = $('.yellowSquare')
$yellowSquarePrev = $yellowSquare.prev();
$yellowSquare.removeClass('yellowSquare');
$yellowSquarePrev.addClass('yellowSquare');
});
#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;
}
.yellowSquare {
background-color: yellow;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="grid-box"></div>
<button id="button_left">left</button>
<button id="button_right">right</button><br>

Link Background Color to Scroll Position

I want to link the background color of the body element to the scroll position such that when the page is scrolled all the way to the top its color 1, but then but then when its scrolled past screen.height, its a completely different color, but I want it to be interpolated such that when it is half-way scrolled, the color is only half-way transitioned. So far, I have it linked to
$(window).scrollTop() > screen.height
and
$(window).scrollTop() < screen.height
to add and remove a class that changes background-color but I want it to be dependent on scroll position not just to trigger the event, but rather smoothly animate it so fast scrolling transitions quickly, slow scrolling transitions it slowly.

One of possible solutions is to bind a rgb color to current height, count the step and set new rgb color depending on current position of scrolling. Here I've created the simplest case - black and white transition:
const step = 255 / $('#wrapper').height();
const multiplier = Math.round(
$('#wrapper').height() /
$('#wrapper').parent().height()
);
$('body').scroll(() => {
const currentStyle = $('body').css('backgroundColor');
const rgbValues = currentStyle.substring(
currentStyle.lastIndexOf("(") + 1,
currentStyle.lastIndexOf(")")
);
const scrolled = $('body').scrollTop();
const newValue = step * scrolled * multiplier;
$('#wrapper').css('background-color', `rgb(${newValue}, ${newValue}, ${newValue})`);
});
html,
body {
padding: 0;
margin: 0;
width: 100%;
height: 100%;
overflow-x: hidden;
background-color: rgb(0, 0, 0);
}
#wrapper {
height: 200%;
width: 100%;
overflow: hidden;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<section id="wrapper"></section>
And here is another one example with transition from yellow to blue:
const step = 255 / $('#wrapper').height();
const multiplier = Math.round(
$('#wrapper').height() /
$('#wrapper').parent().height()
);
$('body').scroll(() => {
const currentStyle = $('body').css('backgroundColor');
const rgbValues = currentStyle.substring(
currentStyle.lastIndexOf("(") + 1,
currentStyle.lastIndexOf(")")
);
const scrolled = $('body').scrollTop();
const newValue = step * scrolled * multiplier;
$('#wrapper').css('background-color', `rgb(${255 - newValue}, ${255 - newValue}, ${newValue})`);
});
html,
body {
padding: 0;
margin: 0;
width: 100%;
height: 100%;
overflow-x: hidden;
background-color: rgb(255, 255, 0);
}
#wrapper {
height: 200%;
width: 100%;
overflow: hidden;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<section id="wrapper"></section>

var randomHex = function () {
return (parseInt(Math.random()*16)).toString(16) || '0';
};
var randomColor = function () {
return '#'+randomHex()+randomHex()+randomHex();
};
var randomGradient = function () {
$('.longContent').css('background', 'linear-gradient(0.5turn, #222, '+randomColor()+','+randomColor()+')');
};
$(window).on('load', randomGradient);
body {
margin: 0;
}
.longContent {
height: 400vh;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/tween.js/17.2.0/Tween.min.js"></script>
<div class="longContent"></div>

A much, much easier way to accomplish what you're looking to do is by simply using a gradient as the background.
There is absolutely zero need for any JS here, which will only slow down the page.
body {
height: 600vh;
background: linear-gradient(#2E0854, #EE3B3B)
}
Is there a particular reason you want to do this with JS?

Leap.JS: How can I select items on a webpage using the LeapMotion?

I am looking to select items in a web page using the LeapMotion and I am struggling with programming this interaction.
Using this code as a base (but updating the link so it connects to the current SDK) I can get my cursor to move around the window based on where my hand is in space. However, I do not know how to make the equivalent of the event listener "click" using the LeapMotion. I am using Leap.js and have built a crude GUI using svg.js.
How do I program an event listener that selects using the LeapMotion in Javascript?

I have working code with Leap motion. I did quize software. Here cursor is a div element which styled as:
#cursor {
width: 60px;
height: 60px;
position: fixed;
margin-left: 20px;
margin-top: 20px;
z-index: 99999;
opacity: 0.9;
background: black;
border-radius: 100%;
background: -webkit-radial-gradient(100px 100px, circle, #f00, #ff6a00);
background: -moz-radial-gradient(100px 100px, circle, #f00, #ff6a00);
background: radial-gradient(100px 100px, circle, #f00, #ff6a00);
}
and Java script at bottom. What I did, I get HTML element by position and triggering click event on it by tap gestures.
var w = Math.max(document.documentElement.clientWidth, window.innerWidth || 0);
var h = Math.max(document.documentElement.clientHeight, window.innerHeight || 0);
// Setting cursor and output position
window.cursor = $('#cursor');
var controller= Leap.loop(function(frame) {
if (frame.pointables.length > 0) {
try
{
var position = frame.pointables[0].stabilizedTipPosition;
var normalized = frame.interactionBox.normalizePoint(position);
var cx = w * normalized[0];
var cy = h * (1 - normalized[1]);
$('#cursor').css('left', cx);
$('#cursor').css('top', cy);
}catch(e){
console.error(e);
}
}
});
controller.use('screenPosition', {
scale: 1
});
controller.on('gesture', onGesture);
function onGesture(gesture,frame)
{
try
{
// If gesture type is keyTap
switch(gesture.type)
{
case 'keyTap':
case 'screenTap':
var position = frame.pointables[0].stabilizedTipPosition;
var normalized = frame.interactionBox.normalizePoint(position);
//Hiding cursor for getting background element
cursor.hide();
// Trying find element by position
var cx = w * normalized[0];
var cy = h * (1 - normalized[1]);
var el = document.elementFromPoint(cx, cy);
cursor.show();
console.log(el);
if (el) {
$(el).trigger("click");
}
break;
}
}
catch (e) {
console.info(e);
}
}

Create custom square grid using jquery

I am working on a project trying to make something resembling an etch-a-sketch. I have a 780x780px square, and I am trying to get a 16x16 grid, using a series of smaller square divs.
It is on this grid that I have the hover effect. I keep getting a 15x17 grid of square divs because the last square of the row won't fit. I have margins set to 1px and padding set to 0 so I figured that to fit 16 squares on a 780px wide row, it would require me to take into account the margins (15 1px margins) and from there I could divide (780-15) by 16, the number of squares I want.
That isn't working, and the next step of this project is to have a button where the user could input any number of squares for the row/column and have either a larger or smaller squared grid STILL ON the 780x780 square. Does anyone have any ideas? I'm pretty stumped.
$(document).ready(function() {
var original = 16;
for (var y = 0; y < original * original; y++) {
$(".squares").width((780 - 15) / original);
$(".squares").height((780 - 17) / original);
$("<div class='squares'></div>").appendTo('#main');
}
$('.squares').hover(
function() {
$(this).addClass('hover');
}
)
});
function gridq() {
$('.squares').removeClass('hover');
$('div').remove('.squares');
var newgrid = prompt("How many squares on each side?");
var widthscreen = 192;
if (newgrid > 0) {
for (var x = 0; x < newgrid * newgrid; x++) {
$(".squares").width(widthscreen / newgrid);
$(".squares").height(widthscreen / newgrid);
$("<div class='squares'></div>").appendTo('#main');
}
$('.squares').hover(
function() {
$(this).addClass('hover');
}
)
}
}
#main {
height: 780px;
width: 780px;
background-color: antiquewhite;
position: relative;
}
.squares {
margin: 1px;
padding: 0;
background-color: aquamarine;
display: inline-block;
float: left;
}
.hover {
background-color: red;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
<div id=main>
</div>
<button onclick="gridq()">Go Again!</button>

Try this snippet? Grid initialisation is set in the grid() function and then called later when necessary. The width is set dynamically to the 16th square's right side.and the remaining squares fill out as necessary.
var wide = (780 - 15) / 16,
tall = (780 - 17) / 16; // set the square dimensions. this can be incorporated into the grid() function with 16 replaced by 'original'
function grid(x, y) {
var original = x,
y = y;
$("#main").empty(); // empty and restart
$("#main").width(wide * (original + 1));
for (var i = 0; i < original * y; i++) {
$("<div class='squares'></div>").appendTo('#main');
}
var square = $(".squares");
square.width(wide);
square.height(tall);
var side = square.eq(original - 1).position().left + square.width() + 2; // tighten the #main width
$("#main").width(side);
$('.squares').hover(
function() {
$(this).addClass('hover');
}
)
}
grid(16, 16); // starting dimension
function gridq() {
$('.squares').removeClass('hover');
$('div').remove('.squares');
var newgrid = prompt("How many squares on each side?");
var widthscreen = 192;
if (newgrid > 0) {
grid(newgrid, newgrid);
}
}
#main {
background-color: antiquewhite;
position: relative;
}
.squares {
margin: 1px;
padding: 0;
background-color: aquamarine;
display: inline-block;
float: left;
}
.hover {
background-color: red;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
<div id='main'>
</div>
<button onclick="gridq()">Go Again!</button>

just got beat to it...ill post this as it answers the question slightly differently and I feel is a little cleaner. Also I added in a width and a height prompt.
see the codepen here
As a side note...its good practice to make the names of your variables make sense. Also I find that breaking down your code problems into smaller more manageable chunks makes it seem less overwhelming...one step at a time :)
Enjoy and good luck!
$(document).ready(function() {
//declare the variables at the top of your functions...it enables us to change them later
var columnWidthCount = 16;
var columnHeightCount = 16;
function makeBoxes() {
//boxcount lets us set how many times we want the for loop to run...when we change the columns/rows later this variable will be updated
var boxCount = columnWidthCount * columnHeightCount;
//
for (var i = 0; i < boxCount; i++) { //loop through each box
//any code you place in here will execute each time we loop around
$("<div class='squares'></div>").appendTo('#main');
}
//we only want to declare this once so we place it after the loop
$(".squares").width((780 / columnWidthCount) - 2);
$(".squares").height((780 / columnHeightCount) - 2);
$('.squares').hover(
function() {
$(this).addClass('hover');
}
);
}
//fire the initial function
makeBoxes();
// fire function after click
$('button').on("click", function() {
$('div').remove('.squares');
var squaresHigh = prompt("How many squares high? (must be a number)");
var squaresWide = prompt("How many squares wide? (must be a number)");
//prompt returns a string...use parseInt to turn that number string into an integer
columnWidthCount = parseInt(squaresWide);
columnHeightCount = parseInt(squaresHigh);
makeBoxes();
});
});
#main {
height: 780px;
width: 780px;
background-color: antiquewhite;
position: relative;
font-size:0;
white-space:nowrap;
}
.squares {
margin: 1px;
padding: 0;
background-color: aquamarine;
display: inline-block;
float: left;
}
.hover {
background-color: red;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
<div id=main>
</div>
<button>Go Again!</button>

How can I make my div element move more than 200px?

I've been working on a project using jQuery where i have a div element that says "click," and when you try to click on it, it moves to a random location within the window. The issue I'm having is that every once in a while the div will move only a little bit, leaving the cursor still inside of the div, allowing the user to click on the link.
I'm fairly new at javascript and I'm not too sure how I should go about doing something like this.
I was thinking I could do something like subtracting the new position from the old one and checking to see if they have a difference of less than 200px, and if they do, recalculating the numbers. If that isn't how you would do it, I'm completely open to other methods.
function setPosition() {
var randY = Math.floor(Math.random() * (window.innerHeight - 200));
var randX = Math.floor(Math.random() * (window.innerWidth - 200));
$('#square').animate({
top: randY + 'px',
left: randX + 'px'
}, 200);
}
$(document).ready(function() {
setPosition()
var tries = 0;
//tries is just to stop it after it reaches 1000.
//I'm planning to make some kind of page to congradulate you on wasting your time.
$('#square').mouseenter(function() {
if (tries < 1000) {
setPosition();
tries += 1;
console.log(tries)
}
});
});
#square {
background: orange;
height: 115px;
width: 150px;
position: relative;
text-align: center;
padding-top: 35px;
}
h3,
h3 * {
font-family: "Comic Sans MS", cursive, sans-serif;
font-size: 20px;
vertical-align: middle;
position: relative;
color: black;
text-decoration: none;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<html>
<head>
<link rel=stylesheet type=text/css href=square.css>
<script src=jquery-1.11.3.min.js></script>
<script src=square.js></script>
</head>
<body>
<div id=square>
<h3><a href=''>Click</a></h3>
</div>
</body>
</html>

I'm thinking you might want to run your randomization logic until it finds a combination that is more than 200 pixels away from it's current location.
Off the top of my head, that'd be something like this:
function setPosition() {
var $square = $('#square');
var prevY = $square.offset().top;
var prevX = $square.offset().left;
var randY, randX;
do {
randY = Math.floor(Math.random() * (window.innerHeight - 200));
randX = Math.floor(Math.random() * (window.innerWidth - 200));
} while( Math.abs(randY - prevY) < 200 || Math.abs(randX - prevX) < 200 );
$square.animate({
top: randY + 'px',
left: randX + 'px'
}, 200);
}