Develop Reference

How to give an animation to border

I have a div that has a gradient border. So I want to give this div an animation and as soon as it is scrolled to this div, I want border-gradient turn around itself. I have no idea how to do it that's why I am asking it direcly.
<div class="border-gradient">
</div>
.border-gradient {
height: 230px;
width: 100%;
border: 5px solid transparent;
border-image: linear-gradient(190deg, rgba(205, 0, 98,0) 10%, rgba(205, 0, 98,0.5));
border-image-slice: 1;
}

I was unable to find a css solution for animating the border, it may be achievable using images.
Anyways, here is a javascript solution
var bored = document.getElementsByClassName("border-gradient")[0];
var anim = {'running':0,'deg':0,'time':0};
var animator;
var boredy = bored.getBoundingClientRect().top;//grab the y of the element relative to the top of the web page
checkscroll();//check if element onscreen initially
window.onscroll = checkscroll;//check if element is onscreen when the user scrolls
function checkscroll() {
if(!anim.running && window.scrollY + window.innerHeight >= boredy) {
anim.running = 1; anim.time = 0;//reset the animation, set running to 1 so the animation won't retrigger while already running
startanim();
}
}
function startanim() {
animator = setInterval(function() {
anim.deg += 1;
anim.time += 50;
bored.style = `border-image:linear-gradient(${anim.deg}deg, rgba(205, 0, 98,0) 10%, rgba(205, 0, 98,0.5)); border-image-slice: 1;`;
if(anim.time >= 10000){window.clearInterval(animator); anim.running = 0}
},50);//start a loop that continousouly updates the border
}
Css:
.border-gradient {
height: 230px;
width: 100%;
border: 5px solid transparent;
border-image: linear-gradient(0deg, rgba(205, 0, 98,0) 10%, rgba(205, 0, 98,0.5));
border-image-slice: 1;
margin-top:150vh;
}
Improvements can certainly be made. So play around with it and tweak it to your liking.

you can animate border as:
.border-gradient {
border: solid 5px #FC5185;
transition: border-width 0.6s linear;
}
.border-gradient:hover { border-width: 10px; }

Vertical dragBar for resizing two divs

I wanted a vertical dragBar for resizing two divs. I have created an example for the same but I am facing an issue.
Actual : As and when I resize the the upper div and move the slider down, the area of parent div increases and hence a scroll bar is given.
Expected: When Resizing, if the slider is moved down, it should only show the data contained in the upper div and when slider is moved up, it should show the content of lower div and should not increase the over all length of the parent div.
var handler = document.querySelector('.handler');
var wrapper = handler.closest('.wrapper');
var boxA = wrapper.querySelector('.box1');
var boxB = wrapper.querySelector('.box2');
var isHandlerDragging = false;
document.addEventListener('mousedown', function(e) {
// If mousedown event is fired from .handler, toggle flag to true
if (e.target === handler) {
isHandlerDragging = true;
}
});
document.addEventListener('mousemove', function(e) {
// Don't do anything if dragging flag is false
if (!isHandlerDragging) {
return false;
}
// Get offset
var containerOffsetTop= wrapper.offsetTop;
var containerOffsetBottom= wrapper.offsetBottom;
// Get x-coordinate of pointer relative to container
var pointerRelativeXpos = e.clientY - containerOffsetTop;
var pointerRelativeXpos2 = e.clientY - e.offsetTop + e.offsetHeight;
var boxAminWidth = 30;
boxA.style.height = (Math.max(boxAminWidth, pointerRelativeXpos - 2)) + 'px';
boxA.style.flexGrow = 0;
boxB.style.height = (Math.max(boxAminWidth, pointerRelativeXpos2 - 8)) + 'px';
boxB.style.flexGrow = 0;
});
document.addEventListener('mouseup', function(e) {
// Turn off dragging flag when user mouse is up
isHandlerDragging = false;
});
body {
margin: 40px;
}
.wrapper {
background-color: #fff;
color: #444;
/* Use flexbox */
}
.box1, .box2 {
background-color: #444;
color: #fff;
border-radius: 5px;
padding: 20px;
font-size: 150%;
margin-top:2%;
/* Use box-sizing so that element's outerwidth will match width property */
box-sizing: border-box;
/* Allow box to grow and shrink, and ensure they are all equally sized */
}
.handler {
width: 20px;
height:7px;
padding: 0;
cursor: ns-resize;
}
.handler::before {
content: '';
display: block;
width: 100px;
height: 100%;
background: red;
margin: 0 auto;
}
<div class="wrapper">
<div class="box1">A</div>
<div class="handler"></div>
<div class="box2">B</div>
</div>
Hope I was clear in explaining the issue I am facing in my project. Any help is appreciated.

It looks like your on the right track. You just need to make the wrapper a flexbox with the flex direction column and assign it a height. Also box 2 needs to have a flex of 1 so it can grow and shrink as needed. Finally I needed to remove the code that set the flex grow to 0 in the JavaScript. Here is the result.
var handler = document.querySelector('.handler');
var wrapper = handler.closest('.wrapper');
var boxA = wrapper.querySelector('.box1');
var boxB = wrapper.querySelector('.box2');
var isHandlerDragging = false;
document.addEventListener('mousedown', function(e) {
// If mousedown event is fired from .handler, toggle flag to true
if (e.target === handler) {
isHandlerDragging = true;
}
});
document.addEventListener('mousemove', function(e) {
// Don't do anything if dragging flag is false
if (!isHandlerDragging) {
return false;
}
e.preventDefault();
// Get offset
var containerOffsetTop= wrapper.offsetTop;
var containerOffsetBottom= wrapper.offsetBottom;
// Get x-coordinate of pointer relative to container
var pointerRelativeXpos = e.clientY - containerOffsetTop;
var pointerRelativeXpos2 = e.clientY - e.offsetTop + e.offsetHeight;
var boxAminWidth = 30;
boxA.style.height = (Math.max(boxAminWidth, pointerRelativeXpos - 2)) + 'px';
boxB.style.height = (Math.max(boxAminWidth, pointerRelativeXpos2 - 8)) + 'px';
});
document.addEventListener('mouseup', function(e) {
// Turn off dragging flag when user mouse is up
isHandlerDragging = false;
});
body {
margin: 40px;
}
.wrapper {
background-color: #fff;
color: #444;
/* Use flexbox */
display: flex;
flex-direction: column;
height: 200px;
}
.box1, .box2 {
background-color: #444;
color: #fff;
border-radius: 5px;
padding: 20px;
font-size: 150%;
margin-top:2%;
/* Use box-sizing so that element's outerwidth will match width property */
box-sizing: border-box;
/* Allow box to grow and shrink, and ensure they are all equally sized */
}
.box2 {
flex: 1;
}
.handler {
width: 20px;
height:7px;
padding: 0;
cursor: ns-resize;
}
.handler::before {
content: '';
display: block;
width: 100px;
height: 100%;
background: red;
margin: 0 auto;
}
<div class="wrapper">
<div class="box1">A</div>
<div class="handler"></div>
<div class="box2">B</div>
</div>

How to drag or move a span into the Div by using javascript

How to move or drag the span into the Div element. My element structure is the Div -> Span. Here I need to drag the Span inside the div element without drag beyond that div. I have tried this by calculating pixels but didn't give a solution. I don't need a native onDrag method.
I need to calculate pixels and drag the Span inside the Div. Here is my code.
var handleClick = false;
window.dragging = function(event) {
if (handleClick) {
var bar = document.getElementsByClassName('bar')[0],
handle = document.getElementsByClassName('handle')[0];
var left = bar.offsetWidth - handle.offsetWidth;
tops = (bar.offsetWidth - handle.offsetWidth);
pixel = left < ((pixel - 0) / 1.233445) ? left : ((pixel - 0) / 1.233445);
handle.style.left = pixel + "px";
}
}
document.addEventListener('mouseup', function() {
handleClick = false;
});
window.handlersDown = function() {
handleClick = true;
}
.bar {
width: 100px;
height: 30px;
border: 1px solid;
position: relative;
}
.handle {
width: 20px;
height: 20px;
left: 2px;
top: 5px;
background-color: rgba(255, 0, 0, 0.5);
position: absolute;
}
<div class="bar">
<span class="handle" onmousedown="handlersDown()" onmousemove="dragging(event)"></span>
</div>

I have modified your code a bit and changed the selectors from class to ID. I also would advice you to use external libraries to make it more easy for you. Besides that I also removed the event listeners inside your HTML and translate them to Javascript. Is this what you want?
window.onload = addListeners();
function addListeners(){
document.getElementById('handle').addEventListener('mousedown', mouseDown, false);
window.addEventListener('mouseup', mouseUp, false);
}
function mouseUp()
{
window.removeEventListener('mousemove', spanMove, true);
}
function mouseDown(e){
window.addEventListener('mousemove', spanMove, true);
}
function spanMove(e){
var bar = document.getElementById('bar')
var span = document.getElementById('handle');
// variables
var bar_width = bar.offsetWidth;
var handle_width = span.offsetWidth;
// stop scroll left if the minimum and maximum is reached
if(e.clientX < bar_width - handle_width - 1 && e.clientX > 1){
span.style.left = e.clientX + 'px';
}
}
#bar {
width: 100px;
height: 30px;
border: 1px solid;
position: relative;
}
#handle {
width: 20px;
height: 20px;
left: 2px;
top: 5px;
background-color: rgba(255, 0, 0, 0.5);
position: absolute;
}
<div id="bar">
<span id="handle"></span>
</div>

In 2020, following solution works perfectly on last version of Chrome, Opera, Firefox and Edge Chromium.
window.onload = addListeners();
function addListeners()
{
var div = document.getElementById('div');
var span = document.getElementById('span');
span.addEventListener('mousedown', onMouseDown, false);
window.addEventListener('mouseup', onMouseUp, false);
//compute space between left border of <div> and left border of <span>
// this value is also used to compute space at right
iMinLeft = span.offsetLeft;
// compute max left value allowed so that span remains in <div>
iMaxLeft = div.clientWidth - span.offsetWidth - iMinLeft;
}
function onMouseDown(e)
{
if (e.which === 1) // left button is pressed
{
e.preventDefault();
window.addEventListener('mousemove', onMouseMove, true);
// save mouse X position to compute deplacement
posMouseX = e.clientX;
span.style.background = "yellow";
}
}
function onMouseMove(e)
{
e.preventDefault();
//compute mouse deplacement
deltaX = posMouseX - e.clientX;
//compute new left position of <span> element
iNewLeft = span.offsetLeft - deltaX;
if (iNewLeft < iMinLeft)
{
iNewLeft = iMinLeft;
}
else
{
if (iNewLeft > iMaxLeft)
{
iNewLeft = iMaxLeft;
}
}
span.style.left = iNewLeft + 'px';
// save mouse X position to compute NEXT deplacement
posMouseX = e.clientX;
}
function onMouseUp(e)
{
if (e.which === 1) // left button is pressed
{
e.preventDefault();
span.style.background = "white";
window.removeEventListener('mousemove', onMouseMove, true);
}
}
#div
{
width: 200px;
height: 50px;
border: 1px solid;
position: relative;
left: 50px;
}
#span
{
cursor: pointer;
font-size: 30px;
width: auto;
height: 40px;
left: 2px;
top: 5px;
position: absolute;
}
<div id="div">
<span id="span">&#x1F603</span>
</div>
JavaScript line e.preventDefault(); is necessary to avoid <span> to become 'blue' when dragging.
CSS code cursor: pointer; is only to see that unicode is clickable.
Javascript line if (e.which === 1) has been added to prevent emoticon to move when RIGHT mouse button is clicked.
The rectangle around emoticon when <span> is dragged move without being shifted (see previous solution) and space remaining in left or in right are equal.
Thanks to w3schools-exemple

Check if element is partially in viewport

I'm trying to determine if an element is partially or fully in the viewport.
I've found this which will determine if an element is fully in view but kept getting confused when trying to determine partial visibility. I don't want to use jQuery.
Basically, the idea is that there will be an element on the page that could be out of view. Once the user scrolls that element into view, even partially, it should trigger an event. I'll handle the event trigger by binding an onscroll event. I just need the detection to work properly.
function isInViewport(element) {
var rect = element.getBoundingClientRect();
var html = document.documentElement;
return (
rect.top >= 0 &&
rect.left >= 0 &&
rect.bottom <= (window.innerHeight || html.clientHeight) &&
rect.right <= (window.innerWidth || html.clientWidth)
);
}
Any help would be greatly appreciated!

Late answer, but about a month ago I wrote a function that does exactly that, it determines how much an element is visible measured in percent in the viewport. Ive tested it in chrome, firefox, ie11, ios on iphone/ipad. The function returns true when X percent (as a number from 0 to 100) of the element is visible. Only determines if the measurements of the element are visible and not if the element is hidden with opacity, visibility etc..
const isElementXPercentInViewport = function(el, percentVisible) {
let
rect = el.getBoundingClientRect(),
windowHeight = (window.innerHeight || document.documentElement.clientHeight);
return !(
Math.floor(100 - (((rect.top >= 0 ? 0 : rect.top) / +-rect.height) * 100)) < percentVisible ||
Math.floor(100 - ((rect.bottom - windowHeight) / rect.height) * 100) < percentVisible
)
};

You need a solution based on element.offsetTop, element.offsetLeft, element.offsetHeight, element.offsetWidth, window.innerWidth and window.innerHeight
(depending on the situation, you might also want to take the scrolling position into consideration)
function isInViewport(element){
if(element.offsetTop<window.innerHeight &&
element.offsetTop>-element.offsetHeight
&& element.offsetLeft>-element.offsetWidth
&& element.offsetLeft<window.innerWidth){
return true;
} else {
return false;
}
}
function test(){
alert(isInViewport(document.getElementById("elem"))?"Yes":"No");
}
#elem{width: 20px; height: 20px; background: red; }
#elem{position: absolute;top: -9px;left: 600px;}
<div id="elem"></div>
<button onclick="test()">Check</button>

function partInViewport(elem) {
let x = elem.getBoundingClientRect().left;
let y = elem.getBoundingClientRect().top;
let ww = Math.max(document.documentElement.clientWidth, window.innerWidth || 0);
let hw = Math.max(document.documentElement.clientHeight, window.innerHeight || 0);
let w = elem.clientWidth;
let h = elem.clientHeight;
return (
(y < hw &&
y + h > 0) &&
(x < ww &&
x + w > 0)
);
}
document.addEventListener("scroll", ()=>{
let el = document.getElementById("test");
if (partInViewport(el)) {
document.getElementById("container").style.backgroundColor = "green";
} else {
document.getElementById("container").style.backgroundColor = "red";
}
});
#test {
height: 200px;
width: 145px;
background-color: grey;
}
#container {
height: 400px;
width: 345px;
transform: translate(400px, 360px);
background-color: red;
display: grid;
align-items: center;
justify-items: center;
}
body {
height: 1500px;
width: 1500px;
}
<div id="container">
<div id="test"></div>
</div>
My example for this code:
https://jsfiddle.net/xqpebwtv/27/

The modern way on how to handle this would be Intersection Observer (IO). With IO you can observe (as the name suggest) elements and trigger actions whenver an alement comes into view. You can set the percentages at which the observer is triggered (e.g. 10% in view, 90% in view, ... )
I really like this example from the linked page, there you have 4 different elements. Each with a different trigger percentage.
let observers = [];
startup = () => {
let wrapper = document.querySelector(".wrapper");
// Options for the observers
let observerOptions = {
root: null,
rootMargin: "0px",
threshold: []
};
// An array of threshold sets for each of the boxes. The
// first box's thresholds are set programmatically
// since there will be so many of them (for each percentage
// point).
let thresholdSets = [
[],
[0.5],
[0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0],
[0, 0.25, 0.5, 0.75, 1.0]
];
for (let i = 0; i <= 1.0; i += 0.01) {
thresholdSets[0].push(i);
}
// Add each box, creating a new observer for each
for (let i = 0; i < 4; i++) {
let template = document.querySelector("#boxTemplate").content.cloneNode(true);
let boxID = "box" + (i + 1);
template.querySelector(".sampleBox").id = boxID;
wrapper.appendChild(document.importNode(template, true));
// Set up the observer for this box
observerOptions.threshold = thresholdSets[i];
observers[i] = new IntersectionObserver(intersectionCallback, observerOptions);
observers[i].observe(document.querySelector("#" + boxID));
}
// Scroll to the starting position
document.scrollingElement.scrollTop = wrapper.firstElementChild.getBoundingClientRect().top + window.scrollY;
document.scrollingElement.scrollLeft = 750;
}
intersectionCallback = (entries) => {
entries.forEach((entry) => {
let box = entry.target;
let visiblePct = (Math.floor(entry.intersectionRatio * 100)) + "%";
box.querySelector(".topLeft").innerHTML = visiblePct;
box.querySelector(".topRight").innerHTML = visiblePct;
box.querySelector(".bottomLeft").innerHTML = visiblePct;
box.querySelector(".bottomRight").innerHTML = visiblePct;
});
}
startup();
body {
padding: 0;
margin: 0;
}
svg:not(:root) {
display: block;
}
.playable-code {
background-color: #f4f7f8;
border: none;
border-left: 6px solid #558abb;
border-width: medium medium medium 6px;
color: #4d4e53;
height: 100px;
width: 90%;
padding: 10px 10px 0;
}
.playable-canvas {
border: 1px solid #4d4e53;
border-radius: 2px;
}
.playable-buttons {
text-align: right;
width: 90%;
padding: 5px 10px 5px 26px;
}
.contents {
position: absolute;
width: 700px;
height: 1725px;
}
.wrapper {
position: relative;
top: 600px;
}
.sampleBox {
position: relative;
left: 175px;
width: 150px;
background-color: rgb(245, 170, 140);
border: 2px solid rgb(201, 126, 17);
padding: 4px;
margin-bottom: 6px;
}
#box1 {
height: 300px;
}
#box2 {
height: 175px;
}
#box3 {
height: 350px;
}
#box4 {
height: 100px;
}
.label {
font: 14px "Open Sans", "Arial", sans-serif;
position: absolute;
margin: 0;
background-color: rgba(255, 255, 255, 0.7);
border: 1px solid rgba(0, 0, 0, 0.7);
width: 3em;
height: 18px;
padding: 2px;
text-align: center;
}
.topLeft {
left: 2px;
top: 2px;
}
.topRight {
right: 2px;
top: 2px;
}
.bottomLeft {
bottom: 2px;
left: 2px;
}
.bottomRight {
bottom: 2px;
right: 2px;
}
<template id="boxTemplate">
<div class="sampleBox">
<div class="label topLeft"></div>
<div class="label topRight"></div>
<div class="label bottomLeft"></div>
<div class="label bottomRight"></div>
</div>
</template>
<main>
<div class="contents">
<div class="wrapper">
</div>
</div>
</main>

What your code is saying is that:
The top side of the element must be below the top side of the window,
The left of the element must be to the right of the left side of the window,
The bottom side of the element must be to the top of the bottom side of the window, AND
The right side of the element must be to the left of the right side of the window
What you want:
The top side of the element must be below the top side of the window OR the bottom side of the element must be above the bottom side of the window, AND
The left side of the element must be to the right of the left side of the window OR the right side of the element must be to the left of the right side of the window
Take what you will from that, the code should be simple enough from here.

This should do it, offsets are not needed, since we are comparing client rectangles.
function isPartiallyVisibleInViewport(element, viewport) {
var bound = element.getBoundingClientRect();
var bound2 = viewport.getBoundingClientRect();
return bound.bottom > bound2.top && bound.top < bound2.bottom;
}
This function only checks vertically and must be extended if you also want to check horizontally:
return bound.bottom > bound2.top && bound.top < bound2.bottom && bound.right > bound2.left && bound.left < bound2.right;

Hover events on element covered by higher z-index?

I have a canvas element (canvas-mouse) that spans the whole screen - its purpose is to draw a 50% opacity circle around the mouse of a certain size (grabsize). Also on the page will be a number of images in divs. I want these images to be clickable/hoverable, but I also want the 50% opacity circle in canvas-mouse to appear on top of them.
Is there any way to accomplish this?
HTML:
<canvas id="canvas-mouse" class="fullscreen"></canvas>
<div class="object die"><img src="images/Die_d6.svg"></div>
CSS:
html, body {
width: 100%;
height: 100%;
margin: 2px;
overflow: hidden;
color: #FFFFFF;
background-color: #2C744C;
}
canvas.fullscreen {
position: absolute;
left: 0px;
top: 0px;
z-index: -1;
}
.object {
position: absolute;
}
#canvas-mouse {
z-index: 10;
}
JavaScript:
CanvasRenderingContext2D.prototype.drawCircle = function(xpos, ypos, radius, linewidth, linecolor, fill) {
if(typeof(linewidth)==="undefined") {
linewidth = 1;
}
if(typeof(linecolor)==="undefined") {
linecolor = "#000000";
}
this.beginPath();
this.arc(xpos, ypos, radius, 0, 2*Math.PI, false);
this.lineWidth = linewidth;
if(typeof(fill)!=="undefined") {
this.fillStyle = fill
this.fill();
}
this.strokeStyle = linecolor;
this.stroke();
}
CanvasRenderingContext2D.prototype.maximize = function() {
this.canvas.width = window.innerWidth;
this.canvas.height = window.innerHeight;
}
mousectx = $("#canvas-mouse")[0].getContext("2d");
mousectx.maximize();
//Dice handlers
$(".object.die").hover(function() {
//Hover event goes here
})
$(".object.die").mousedown(function() {
//Click event goes here
})
//Mouse movement handler
$(document).mousemove(function(e){
//Get the mouse positions and put them in {mouse}
mouse.x = e.pageX;z
mouse.y = e.pageY;
//Redraw the grab circle
mousectx.clearCanvas();
mousectx.drawCircle(mouse.x,mouse.y,grabsize,1,"#000000","rgba(0,0,255,0.5)");
});
Thanks in advance.

Try using pointer-events: none. This rule tells the browser to ignore an element. Mouse events won't be received by it, but will 'pass through'.
#canvas-mouse {
z-index: 10;
pointer-events: none;
}