Develop Reference

How to get the same scrollY height number on different screen sizes?

So I want to add a class on a specific screen height. So I've done:
window.onscroll = function() {scrollPost()};
function scrollPost () {
var x = window.screen.width;
var i = window.scrollY;
var a = i / x;
animator (a);
slide(a);
}
function slide(x){
var a = (x * 100);
var i = Math.round(a);
console.log(i);
var slideIn = document.querySelector(".slide-in-right");
var slideOut = document.querySelector(".slide-out-left");
if (i >= 90){
slideOut.classList.add("animate");
slideIn.classList.add("animate");
slideIn.style.display = ("block");
}
The problem however. Is that on different screens, the value will be different. Thus therefore on different screens it will toggle at a different time. I could probably make ifstatements, based on screen width. But then I'd need a whole lot of them.
I want the animation to be added only after the container is 100% in the screen height. How would you do this?

You are going to have to get users viewport (window height).
Divide it by half
Add it towards your IF position.
I wrote a simular answer, how ever it was written jQuery, if you are considering it would be a better output.
How to trigger a class that is only in view with wapoints
However to implement that to plain js:
Get user screen height:
var w = window,
d = document,
e = d.documentElement,
g = d.getElementsByTagName('body')[0],
x = w.innerWidth || e.clientWidth || g.clientWidth,
y = w.innerHeight|| e.clientHeight|| g.clientHeight;
alert(x + ' × ' + y);
divide y by half, and then add to your current position that checks if element is scrolled.
I will add this just in case. To get element position.
function getPosition(element) {
var xPosition = 0;
var yPosition = 0;
while(element) {
xPosition += (element.offsetLeft - element.scrollLeft + element.clientLeft);
yPosition += (element.offsetTop - element.scrollTop + element.clientTop);
element = element.offsetParent;
}
return { x: xPosition, y: yPosition };
}
Source: How to get the distance from the top for an element?

Variable keeps growing even if condition is not met

I'm trying to animate a div on scroll. The point is that the div's width must grow until it reaches 80vw and stop. This does happen, but my variable keeps on growing (it's being logged to the console) even if the >=outerWidth*0.8 condition isn't met. Thanks to this, whenever I get to 80vw and scroll up and then down, the width becomes Xvw.
$(window).on('scroll',function(){
var scrollTop = $(this).scrollTop();
var outerHeight = $(this).outerHeight();
var outerWidth = $(this).outerWidth();
var scrollBottom = scrollTop + outerHeight;
var scrollTop = $(this).scrollTop();
console.log( growNaranja );
if (scrollTop > lastScrollTop){ // scroll down
if( naranjaWidth <= (outerWidth*0.8) ){
growNaranja = (naranja.outerWidth()*100) / outerWidth;
growNaranja = growNaranja+(scrollTop*0.05);
$('.grow.naranja').css( 'width', growNaranja + 'vw' );
}
} else { // scroll up
if( naranjaWidth >= (outerWidth*0.1) ){
growNaranja = (naranja.outerWidth()*100) / outerWidth;
$('.grow.naranja').css( 'width', growNaranja + 'vw' );
growNaranja = growNaranja - ((lastScrollTop-scrollTop)*0.05);
$('.grow.naranja').css( 'width', growNaranja + 'vw' );
}
}
lastScrollTop = scrollTop;
});
You can see a working example here.

Revisited this one, it was bugging me. First, the code was all spaghetti. Second, there was really function duplication. You had a function for scrolling up and one for scrolling down, and you were using the last scrollTop to calculate the next scroll step. Instead, I've made a single scale function that gets called regardless. The value of the percentage scrolled is multiplied by the step factor, and that is added to the ORIGINAL element width. By doing this, I'm not worried about where I was just prior to the scroll, only where I am now.
So I made the scaleWidthEl an object constructor, and simply wrapped the naranja div in that. The actual code to create it is the first three lines, and could be reduced to:
var scaleNaranja = new ScaleWidthEl($('.grow.naranja'), 0.8);
The rest is self-contained, allowing changes to be made without affecting anything else.
var maxElScale = 0.8;
var naranja = $('.grow.naranja');
var scaleNaranja = new ScaleWidthEl(naranja, maxElScale);
/***
* The rest of this is a black-box function, walled away from the main code
* It's a personal peeve of mine that code gets garbled otherwise.
***/
function ScaleWidthEl(el, maxScale) {
// I don't need a minScale, as I use the initial width for that
this.el = el;
this.vwConversion = (100 / document.documentElement.clientWidth);
this.startingWidth = el.outerWidth();
this.maxScale = maxScale;
this.max = $(window).outerWidth() * this.maxScale;
this.step = (this.max - this.startingWidth) / $(window).outerHeight();
// for the sake of clarity, store a reference to `this` for
// any nested functions.
var that = this;
/**
* function scaleEl
* handle the actual scaling of the element.
* Using a given step, we will simply add that
* to the element's current width, then update the CSS
* width property of the element.
**/
this.scaleEl = function() {
// First, calculate the percentage of vertical scroll
var winheight = $(window).height();
var docheight = $(document).height();
var scrollTop = $(window).scrollTop();
var trackLength = docheight - winheight;
// gets percentage scrolled (ie: 80 NaN if tracklength == 0)
var pctScrolled = Math.floor(scrollTop / trackLength * 100);
// console.log(pctScrolled + '% scrolled')
// Now, using the scrolled percentage, scale the div
var tempWidth = this.startingWidth * this.vwConversion;
tempWidth += pctScrolled * this.step;
// I want to fix the max of the scale
if (tempWidth > (this.maxScale * 100)) {
tempWidth = this.maxScale * 100;
}
this.el.css('width', tempWidth + 'vw');
};
$(window).on("scroll", function() {
that.scaleEl();
}).on("resize", function() {
/**
* In the case of a resize, we should
* recalculate min, max and step.
**/
that.min = $(window).outerWidth() * that.minScale;
that.max = $(window).outerWidth() * that.maxScale;
that.step = (that.max - that.min) / $(window).outerHeight();
})
}
body {
height: 10000px;
}
.grow {
position: fixed;
height: 100vh;
top: 0;
left: 0;
}
.grow.gris {
width: 35vw;
z-index: 2;
background: silver;
}
.grow.naranja {
width: 10vw;
z-index: 1;
background: orange;
}
<script src="https://code.jquery.com/jquery-3.1.1.min.js" crossorigin="anonymous"></script>
<div class="grow naranja"></div>
<!-- .naranja -->

Limiting an element from appearing out of the screen

I'm trying to make a square appear at random positions of the screen. I have set it's position property to be absolute and in javascript i'm running a random number between 0 to 100, this will then be assigned as a percentage to top and left property. however if the random number was ~100 or a bit less the square will appear out of the screen. How do I fix this problem?
var shape1 = document.getElementById("shape1");
//creating random number to 100
function randomNum() {
var r = Math.random();
var y = (r * (100 - 0 + 1)) + 0;
var x = Math.floor(y);
console.log(x);
return x;
}
//reappear at random position
function reappear(object) {
object.style.left = randomNum().toString() + "%";
object.style.top = randomNum().toString() + "%";
object.style.display = "block";
}
reappear(shape1);
code: https://jsfiddle.net/y3m4ygow/1/

You can call the getBoundingClientRect method (MDN reference) on the object and check to see if its bottom property is bigger than window.innerHeight (means it's falling outside the window height), or if its right property is bigger than window.innerWidth (means it's falling outside the window width), and if so, call the reappear function again:
function reappear(object) {
object.style.left = randomNum().toString() + "%";
object.style.top = randomNum().toString() + "%";
object.style.display = "block";
var rect = object.getBoundingClientRect();
if(rect.right > window.innerWidth || rect.bottom > window.innerHeight)
reappear(object);
}
Fiddle update: https://jsfiddle.net/y3m4ygow/2/

As you can see what's happening here is sometimes the object falling out of the document because (the width or height of it + the randomized percentage) is more than document width or height.
For example, say that document width is 1000px and the random number turned out to be 90% (=900px), since the box width is 200px, so you will have 100px out of the screen.
Now you have two solutions:
First: As #Sidd noted, you can check whether the box is in or out using getBoundingClientRect this will return a variable for you having two properties one is bottom which is the distance of the box from the upper edge of the document, the other property is height which is the distance of the box from the left border of the screen.
Now what you can do is compare those two values with the document width and height.
Now by adding those three lines you'll have your problem solved:
var rect = object.getBoundingClientRect(); // getting the properties
if(rect.right > window.innerWidth // comparing width
|| rect.bottom > window.innerHeight) // comparing height
{reappear(object);} // re-randomizing
https://jsfiddle.net/y3m4ygow/2/
this WILL work, but it might produce some flickering with some browsers, and i'm not very comfortable about calling a function inside itself.
Second Solution is: which is what I would prefer you to do, is by not using a percentage, but using a fixed height and width values.
you can get the current height and weight values from the window object and substract your box dimensions from it:
var cHeight = window.innerHeight - 200;
var cWidth = window.innerWidth - 200;
set those two as the maximum value for the top and the right.
function topRandomNum() {
var r = Math.random();
var y = (r * (cHeight - 0 + 1)) + 0;
var x = Math.floor(y);
return x;
}
function rightRandomNum() {
var r = Math.random();
var y = (r * (cWidth - 0 + 1)) + 0;
var x = Math.floor(y);
return x;
}
and here's the fiddle for the second solution: https://jsfiddle.net/uL24u0e4/

Equation for image mouseover pan?

i have a simple jQ script:
a set width/height container
a landscape img (can be bigger or
smaller than container)
when a user mouses over the image, it pans
(no click/drag) until it reaches the end
The equation to move the img to the left is this:
-1(relative mouse-position)*(img width)/(container width)
This works fine, but it leaves a space one the mouse reaches the end of the img.
Fiddle
$("figure img").mousemove( function (e) {
var a = $(this).closest("figure"),
b = $(this).width(),
c = a.width(),
d = (e.clientX - a.offset().left);
$(this).css({
left: -1*(d*b/c)
}, 100);
});
can someone help? I want the img to be completely aligned to the right of the container once the mouse reaches the end.

The correct formula is: -1 * (d/c) * (b - c)
Or, more clearly: -1 * (mouseX / figureWidth) * (imgWidth - figureWidth)
(mouseX / figureWidth) represents the percent of the width of the figure that the mouse is positioned at. It will be a number between 0 and 1.
(imgWidth - figureWidth) represents the biggest X value you want to use to position the image at the opposite side.
Multiplying the percent by the total range of movement gives you the movement amount for the current mouse position!
Updated Fiddle
I suggest using more descriptive variable names such as figureWidth, imgWidth, mouseX etc. Not only will it be easier for you to understand, but it will be easier for people to answer.

This should work: http://jsfiddle.net/0zd5t1wf/4/
i just get the limit value for the left propriety of image (the image width - the figure box)
$("figure img").each( function () {
if($(this).width() >= ($(this).height() * 2.5)) {
$(this)
.attr("class", "panorama")
.mousemove( function (e) {
var a = $(this).closest("figure"),
b = $(this).width(),
c = a.width(),
d = (e.clientX - a.offset().left),
newLeft = -1*(d*b/c),
limitValue = parseInt($(this).width()) - parseInt($("figure").width());
if ( newLeft < 0 && (newLeft *-1) < limitValue ){
$(this).css({
left: newLeft
}, 100);
}
$("#hello").html('why');
});
}
});

jQuery Plug-in to handle mousemove/drag with easing on a hidden div (kind of "inner zoom"

Actually I'm looking for a jQuery plug-in that can handle this:
there is a container with overflow hidden
inside of this is another one, which is way larger
when i move over the div, the part I'm seeing depends on my current position
when I'm in the left top corner I see the top left corner of the inner container
when I'm in the middle i see the middle of the container …
I wrote a little JavaScript that does that:
this.zoom.mousemove( function(event) {
var parentOffset = $(this).parent().offset();
var relativeX = event.pageX - parentOffset.left;
var relativeY = event.pageY - parentOffset.top;
var differenceX = that.zoom.width() - that.pageWidth;
var differenceY = that.zoom.height() - that.pageHeight;
var percentX = relativeX / that.pageWidth;
var percentY = relativeY / that.pageHeight;
if (1 < percentX) {
percentX = 1;
}
if (1 < percentY) {
percentY = 1;
}
var left = percentX * differenceX;
var top = percentY * differenceY;
that.zoom.css('left', -left).css('top', -top);
});
But this isn't very smooth and kinda jumpy, when you enter from another point of the container. So, before reinventing the wheel: Is there one plug in, that does exactly that and has iOS support (drag instead of mouse move)? All zoom plug ins (like Cloud Zoom) are over the top for this purpose and most have no support for dragging on iOS.
And if there's not something like this. How can I make this smoother and cooler. Any approach would be helpful. :)
Many thanks.

So, here is my solution - which works pretty well and is easy to achieve. There could be done some improvement, but to get the idea i'll leave it that way. :)
there is a demo on jsfiddle:
http://jsfiddle.net/insertusernamehere/78TJc/
CSS
<style>
div.zoom_wrapper {
position: relative;
overflow: hidden;
width: 500px;
height: 500px;
border: 1px solid #ccc;
cursor: crosshair;
}
div.zoom_wrapper > * {
position: absolute;
}
</style>
HTML
<div class="zoom_wrapper">
<img id="zoom" src="http://lorempixel.com/output/people-q-c-1020-797-9.jpg" alt="">
</div>
JAVASCRPT
<script>
var zoom = null;
// this function will work even if the content has changed
function move() {
// get current position
var currentPosition = zoom.position();
var currentX = currentPosition.left;
var currentY = currentPosition.top;
// get container size
var tempWidth = zoom.parent().width();
var tempHeight = zoom.parent().height();
// get overflow
var differenceX = zoom.width() - tempWidth;
var differenceY = zoom.height() - tempHeight;
// get percentage multiplied by difference (in pixel) cut by percentage (here 1/4) that is used as "smoothness factor"
var tempX = zoom.data('x') / tempWidth * differenceX / 4;
var tempY = zoom.data('y') / tempHeight * differenceY / 4;
// get real top and left values to move to and the last factor slows it down and gives the smoothness (and it's corresponding with the calculation before)
var left = (tempX - currentX) / 1.25;
var top = (tempY - currentY) / 1.25;
// finally apply the new values
zoom.css('left', -left).css('top', -top);
}
$(document).ready(function () {
zoom = $('#zoom');
//handle mousemove to zoom layer - this also works if it is not located at the top left of the page
zoom.mousemove( function(event) {
var parentOffset = $(this).parent().offset();
zoom.data('x', event.pageX - parentOffset.left);
zoom.data('y', event.pageY - parentOffset.top);
});
// start the action only if user is over the container
zoom.hover(
function() {
zoom.data('running', setInterval( function() { move(); }, 30) );
},
function() {
clearInterval(zoom.data('running'));
}
);
});
</script>
Note:
This one has, of course, no support for touch devices. But for that I use (again)/I can recommend the good old iScroll … :)