javascript, offsetTop, offsetBottom - javascript

I have a paragraph tag in my html id is move, I am trying to move the p tag to slowing fall down while on page load. but my code is not working.......
var speed = 12;
var direction = 1;
var getParagraph = document.getElementById("move");
getParagraph.onmouseover = moving;
function moving() {
var bo = getParagraph.offsetHeight;
var boTop = getParagraph.offsetTop;
var boBottom = boTop + bo;
// When right side of the box goes too far - change direction:
if (boBottom > document.body.offsetHeight) {
direction = -1;
}
// When left side of the box goes too far - change direction:
if (boTop < 0) {
direction = 1;
}
// Recalculate position:
getParagraph.style.Top = (boTop + speed * direction)
}

This is your code with minor changes, and it "works":
JS:
var speed = 12;
var direction = 1;
var getParagraph = document.getElementById("move");
document.getElementById("move").addEventListener("mouseover", moving);
//getParagraph.onmouseover = moving;
function moving() {
console.log("Moving??");
var bo = document.getElementById("move").offsetHeight;
var boTop = document.getElementById("move").offsetTop;
var boBottom = boTop + bo;
// When right side of the box goes too far - change direction:
if (boBottom > document.body.offsetHeight) {
direction = -1;
}
// When left side of the box goes too far - change direction:
if (boTop < 0) {
direction = 1;
}
// Recalculate position:
document.getElementById("move").style.marginTop = (boTop + speed * direction) + "px";
speed++;
}
CSS:
#move {
display : block ;
position : absolute ;
}
Hope it helps.

Related

jquery calculate height and width and animate content behind it

animate content behind h1
if h1 is top of the image don't animate
Currently works fine but I need to calculate the width of the h1 tag as well in order to animate the image just outside the h1.
Basically if the image sits outside the width of the h1 should show.
I hope this is enough clear.
Demo.
js:
// Get the divs that should change
function displayThese() {
var $heading = $('h1');
var h1top = $heading.position().top;
var h1bottom = h1top + $heading.height();
var divs = $('li').filter(function () {
var $e = $(this);
var top = $e.position().top;
var bottom = top + $e.height();
return top > h1bottom || bottom < h1top;
});
return divs;
}
(function fadeInDiv() {
var divs = displayThese();
var elem = divs.eq(Math.floor(Math.random() * divs.length));
if (!elem.is(':visible')) {
elem.prev().remove();
elem.animate({
opacity: 1
}, Math.floor(Math.random() * 1000), fadeInDiv);
} else {
elem.animate({
opacity: (Math.random() * 1)
}, Math.floor(Math.random() * 1000), function () {
window.setTimeout(fadeInDiv);
});
}
})();
$(window).resize(function () {
// Get items that do not change
var divs = $('li').not(displayThese());
divs.css({
opacity: .3
});
});
You just have to use $.fn.width :
var $heading = $('h1');
var h1top = $heading.position().top;
var h1bottom = h1top + $heading.height();
var h1left = $heading.position().left;
var h1right = h1top + $heading.width();
var divs = $('li').filter(function () {
var $e = $(this);
var top = $e.position().top;
var bottom = top + $e.height();
var left = $e.position().left;
var right = left + $e.width();
return top > h1bottom || bottom < h1top || left > h1right || right < h1left;
});
return divs;
Here is a fiddle : http://jsfiddle.net/33Ec8/3/
Is this what you are looking for:
$(<element>).width()
$(<element>).height()
Demo here.

jQuery: change class after conditional is met

I created this site where you have multiple sliders moving vertically using this example on stackoverflow > here < along with this fiddle.
The site when loaded has an overflow: hidden on the body and position fixed on my main content div(div class="content-fs row"). The idea is that when you first arrive on the page, you scroll through each slide and once you hit the last one, the position changes on the main content div(div class="content-fs row") from fixed to static and the overflow: hidden is removed from the body. I'm having trouble writing the conditional statement that says "if its the last slider, change the position." The jquery below is the code i'm using for the site along with the conditional statement that doesn't work.
Any pointers/advice would be greatly appreciated!
jquery:
function scrollLax(){
/*
initialize
*/
var scrollDown = false;
var scrollUp = false;
var scroll = 0;
var $view = $('#portfolio');
var t = 0;
var h = $view.height() - 250;
$view.find('.portfolio-sliders').each(function() {
var $moving = $(this);
// position the next moving correctly
if($moving.hasClass('from-bottom')) {
$moving.css('top', h); // subtract t so that a portion of the other slider is showing
}
// make sure moving is visible
$moving.css('z-index', 10);
});
var $moving = $view.find('.portfolio-sliders:first-child');
$moving.css('z-index', 10);
/*
event handlers
*/
var mousew = function(e) {
var d = 0;
if(!e) e = event;
if (e.wheelDelta) {
d = -e.wheelDelta/3;
} else if (e.detail) {
d = e.detail/120;
}
parallaxScroll(d);
}
if (window.addEventListener) {
window.addEventListener('DOMMouseScroll', mousew, false);
}
window.onmousewheel = document.onmousewheel = mousew;
/*
parallax loop display loop
*/
window.setInterval(function() {
if(scrollDown)
parallaxScroll(4);
else if(scrollUp)
parallaxScroll(-4);
}, 50);
function parallaxScroll(scroll) {
// current moving object
var ml = $moving.position().left;
var mt = $moving.position().top;
var mw = $moving.width();
var mh = $moving.height();
// calc velocity
var fromBottom = false;
var vLeft = 0;
var vTop = 0;
if($moving.hasClass('from-bottom')) {
vTop = -scroll;
fromBottom = true;
}
// calc new position
var newLeft = ml + vLeft;
var newTop = mt + vTop;
// check bounds
var finished = false;
if(fromBottom && (newTop < t || newTop > h)) {
finished = true;
newTop = (scroll > 0 ? t : t + h);
}
// set new position
$moving.css('left', newLeft);
$moving.css('top', newTop);
// if finished change moving object
if(finished) {
// get the next moving
if(scroll > 0) {
$moving = $moving.next('.portfolio-sliders');
if($moving.length == 0)
$moving = $view.find('.portfolio-sliders:last');
//this is where I am trying to add the if conditional statement.
if ('.portfolio-sliders:last')
$('.content-fs.row').css({'position': 'static'});
if('.portfolio-sliders:last' && (mt == 0))
$('html, body').removeClass('overflow');
} else {
$moving = $moving.prev('.portfolio-sliders');
if($moving.length == 0)
$moving = $view.find('.portfolio-sliders:first-child');
//reverse the logic and if last slide change position
if('.portfolio-sliders:first-child')
$('.content-fs.row').css({'position': 'fixed'});
}
}
// for debug
//$('#direction').text(scroll + "/" + t + " " + ml + "/" + mt + " " + finished + " " + $moving.text());
}
}
Your code as it is simply asks whether .portfolio-sliders:last exists. Seems you should be doing:
if ($moving == $('.portfolio-sliders:last') )
or something along those lines, instead checking whether the active slide is the last.

Slide header up if you scroll down and vice versa

Update
I made a repo on GitHub:
https://github.com/yckart/Veil.js
Big thanks to Sargo Darya and Edward J Payton.
I've to create a header which slides up if you scroll down and vice versa. The problem is, that it jumps (if you are in the diff-range between 0-128).
I can not figure out where the problem sits. Any idea how to get this to work correctly?
Here's what I've done so far: http://jsfiddle.net/yckart/rKW3f/
// something simple to get the current scroll direction
// false === down | true === up
var scrollDir = (function (oldOffset, lastOffset, oldDir) {
return function (offset) {
var dir = offset < oldOffset;
if (dir !== oldDir) lastOffset = offset;
oldOffset = offset;
oldDir = dir;
return {dir: dir, last: lastOffset};
};
}());
var header = document.querySelector('header');
var height = header.clientHeight;
addEventListener('scroll', function () {
var scrollY = document.documentElement.scrollTop || document.body.scrollTop;
var dir = scrollDir(scrollY);
var diff = dir.last-scrollY;
var max = Math.max(-height, Math.min(height, diff));
header.style.top = (dir.dir ? max-height : max) + 'px';
});
Another problem is, that if the scroll-direction was changed the first time, nothing happens. However, this could be fixed with an interval, or else.
I believe this is exactly what you want:
var header = $('header'),
headerHeight = header.height(),
treshold = 0,
lastScroll = 0;
$(document).on('scroll', function (evt) {
var newScroll = $(document).scrollTop(),
diff = newScroll-lastScroll;
// normalize treshold range
treshold = (treshold+diff>headerHeight) ? headerHeight : treshold+diff;
treshold = (treshold < 0) ? 0 : treshold;
header.css('top', (-treshold)+'px');
lastScroll = newScroll;
});
Demo on: http://jsfiddle.net/yDpeb/
Try this out:- http://jsfiddle.net/adiioo7/rKW3f/7/
JS:-
var scrollDir = (function (oldOffset, lastOffset, oldDir) {
return function (offset) {
var dir = offset < oldOffset;
if (dir !== oldDir) {
lastOffset = offset;
} else {
offset = offset - height;
}
oldOffset = offset;
oldDir = dir;
return {
dir: dir,
last: lastOffset
};
};
}());
var header = document.querySelector('header');
var height = header.clientHeight;
$(window).scroll(function () {
var scrollY = $(window).scrollTop();
var dir = scrollDir(scrollY);
var diff = dir.last - scrollY;
var max = Math.max(-height, Math.min(height, diff));
max = (dir.dir ? max - height : max);
max = scrollY<height?0:max;
$('header').data('size', 'small');
$('header').stop().animate({
top: max
}, 600);
});
Sargo Darya's answer above is exacty what i was looking for but I found a bug with Webkits inertia scrolling so I made a fix:
// Scrolling Header
var header = $('header'),
headerHeight = header.height(),
offset = 0,
lastPos = 0;
$(document).on('scroll', function(e) {
var newPos = $(document).scrollTop(),
pos = newPos-lastPos;
if (offset+pos>headerHeight) {
offset = headerHeight;
} else if (newPos < 0){ // webkit inertia scroll fix
offset = 0;
} else {
offset = offset+pos;
};
if (offset < 0) {
offset = 0;
} else {
offset = offset;
};
header.css('top', (-offset)+'px');
lastPos = newPos;
});
Adding one line fixed it. If - if scroll position is lower than 0, set header offset at 0.
Demo based on Sargo Darya's - http://jsfiddle.net/edwardomni/D58vx/4/

Event on margin change

I have an element with animated top margin. I need to detect if it isn't too close from the border, and if it is, scroll parent div to lower position, to prevent animated element from hiding. Here is an example:
http://jsfiddle.net/zYYBR/5/
This green box shouldn't be below the red line after clicking the "down" button.
Do you mean this?
var new_margin;
var step = 75;
var limit = $("#max")[0].offsetTop;
$('#down').click(function() {
var goStep = step;
var elHeight = $("#animated")[0].offsetTop + $("#animated")[0].offsetHeight;
if((elHeight + step) > limit)
{
goStep = limit - elHeight;
}
new_margin = goStep + parseInt($('#animated').css('margin-top'));
$("#animated").animate({marginTop: new_margin}, 1000);
});
http://jsfiddle.net/zYYBR/8/
EDIT: Or maybe something like that (of course you can improve the calculation, because currently it's very buggy with scroll):
var new_margin;
var step = 75;
$('#down').click(function () {
scroll(1000);
});
var scrollTimer = null;
$("#container").bind("scroll", function () {
clearTimeout(scrollTimer);
scrollTimer = setTimeout(function () { scroll(1); }, 10);
});
function scroll(speed) {
var scrollStep, animationStep = step;
var currentBoxBottom = $("#animated")[0].offsetTop + $("#animated")[0].offsetHeight;
var nextCurrentBoxBottom = currentBoxBottom + step;
var limit = $("#max")[0].offsetTop + $("#container")[0].scrollTop;
if (nextCurrentBoxBottom > limit) {
if (limit >= $("#container")[0].scrollTop) {
scrollStep = $("#container")[0].scrollTop + nextCurrentBoxBottom - limit;
}
else {
scrollStep = $("#container")[0].scrollTop - nextCurrentBoxBottom - limit;
animationStep = nextCurrentBoxBottom - limit;
}
$("#container")[0].scrollTop = scrollStep;
}
new_margin = animationStep + parseInt($('#animated').css('margin-top'));
$("#animated").animate({ marginTop: new_margin }, speed);
}
http://jsfiddle.net/zYYBR/13/
Do you mean something like this?
I have the same visual result as Alex Dn did, but I added a little extra direction to what I think you're talking about. If it's what you're looking for I'll make updates:
var new_margin;
var step = 75;
var limit = $("#max")[0].offsetTop;
$('#down2').click(function() {
var anim = $("#animated");
var hrOff = $("#max").offset();
var thOff = anim.offset();
new_margin = Math.min(hrOff.top - thOff.top - anim.height(), 75);
console.log(new_margin, hrOff.top, thOff.top);
var st = 0;
if (new_margin < 75) {
st = 75 - new_margin;
//have container scroll by this much?
}
anim.animate({
marginTop: "+=" + new_margin
}, 1000);
});​
​
http://jsfiddle.net/zYYBR/10/

How to add scroll background effect to multiple elements with different settings?

In this demo http://www.htmldrive.net/items/demo/527/Animated-background-image-with-jQuery
This code is for one background only. I want to add multiple background with different direction and speed.
var scrollSpeed = 70;
var step = 1;
var current = 0;
var imageWidth = 2247;
var headerWidth = 800;
var restartPosition = -(imageWidth - headerWidth);
function scrollBg(){
current -= step;
if (current == restartPosition){
current = 0;
}
$('#header').css("background-position",current+"px 0");
}
var init = setInterval("scrollBg()", scrollSpeed);
Currently it has settings for
$('#header').css("background-position",current+"px 0");
In a website I want to use this effect on #footer or #content background also. but with different speed and direction.
And is there any better and more optimized jquery method to achieve same effect?
And can we get same effect using CSS 3, without javascript?
Just saw the OP's answer, but decided to post anyway:
I've created a jQuery plugin to do this:
(function($) {
$.fn.scrollingBackground = function(options) {
// settings and defaults.
var settings = options || {};
var speed = settings.speed || 1;
var step = settings.step || 1;
var direction = settings.direction || 'rtl';
var animStep;
// build up a string to pass to animate:
if (direction === 'rtl') {
animStep = "-=" + step + "px";
}
else if (direction === 'ltr') {
animStep = '+=' + step + "px";
}
var element = this;
// perform the animation forever:
var animate = function() {
element.animate({
backgroundPosition: animStep + " 0px"
}, speed, animate);
};
animate();
};
})(jQuery);
Usage:
$("#header").scrollingBackground({
speed: 50,
step: 50,
direction: 'ltr'
});
This is pretty basic, and assumes that you're background-repeat is 'repeat-x' on the element you call it on. This way, there's no need to reset the background position every so often.
Working example: http://jsfiddle.net/andrewwhitaker/xmtpr/
I could work out the following solution. Am not sure if it is efficient. Will wait for anyone to comment or provide a better option.
Till then...:
var scrollSpeed = 70;
var step = 1;
var current = 0;
var images =
[
{
imageWidth:2247,
imagePath:"images/image1"
},
{
imageWidth:1200,
imagePath:"images/image2"
}
]
var headerWidth = 800;
var imageRotateCount = 0;
var imagesLength = images.length;
$('#header').css("background-image", images[0].imagePath);
function scrollBg(){
var curIndex = imageRotateCount%imagesLength;
var curImage = images[curIndex];
current -= step;
var restartPosition = -(curImage.imageWidth - headerWidth);
if (current == restartPosition){
current = 0;
imageRotateCount++;
curIndex = imageRotateCount%imagesLength;
curImage = images[curIndex];
$('#header').css("background-image", curImage.imagePath);
}
$('#header').css("background-position",current+"px 0");
}
var init = setInterval("scrollBg()", scrollSpeed);

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