So what I want to happen is that when viewing the Span the text is normal but as you scroll down it starts moving until it looks like such:
Before the effect:
While the effect occurs:
The header is represented by spans for each letter. In the initial state, the top pixel value for each is 0. But the idea as mentioned is that that changes alongside the scroll value.
I wanted to keep track of the scroll position through JS and jQuery and then change the pixel value as needed. But that's what I have been having trouble with. Also making it smooth has been another issue.
Use the mathematical functions sine and cosine, for characters at even and odd indices respectively, as the graphs of the functions move up and down like waves. This will create a smooth effect:
cos(x) == 1 - sin(x), so in a sense, each character will be the "opposite" of the next one to create that scattered look:
function makeContainerWiggleOnScroll(container, speed = 0.01, distance = 4) {
let wiggle = function() {
// y-axis scroll value
var y = window.pageYOffset || document.body.scrollTop;
// make div pseudo-(position:fixed), because setting the position to fixed makes the letters overlap
container.style.marginTop = y + 'px';
for (var i = 0; i < container.children.length; i++) {
var span = container.children[i];
// margin-top = { amplitude of the sine/cosine function (to make it always positive) } + { the sine/cosine function (to make it move up and down }
// cos(x) = 1 - sin(x)
var trigFunc = i % 2 ? Math.cos : Math.sin;
span.style.marginTop = distance + distance * trigFunc(speed * y)/2 + 'px';
}
};
window.addEventListener('scroll', wiggle);
wiggle(); // init
}
makeContainerWiggleOnScroll(document.querySelector('h2'));
body {
height: 500px;
margin-top: 0;
}
span {
display: inline-block;
vertical-align: top;
}
<h2>
<span>H</span><span>e</span><span>a</span><span>d</span><span>e</span><span>r</span>
</h2>
Important styling note: the spans' display must be set to inline-block, so that margin-top works.
Something like this will be the core of your JS functionality:
window.addEventListener('scroll', function(e) {
var scrl = window.scrollY
// Changing the position of elements that we want to go up
document.querySelectorAll('.up').forEach(function(el){
el.style.top = - scrl/30 +'px';
});
// Changing the position of elements that we want to go down
document.querySelectorAll('.down').forEach(function(el){
el.style.top = scrl/30 +'px';
});
});
We're basically listening in on the scroll event, checking how much has the user scrolled and then act upon it by offsetting our spans (which i've classed as up & down)
JSBin Example
Something you can improve on yourself would be making sure that the letters wont go off the page when the user scrolls a lot.
You can do this with simple math calculation, taking in consideration the window's total height and using the current scrollY as a multiplier.
- As RokoC has pointed out there is room for performance improvements.Implement some debouncing or other kinds of limiters
Related
I've made up this Horizontal scrolling page based on some idea from YouTube, everything works fine, the logic is also fine, but the translation of x has a problem, sometimes it translates X too much or sometime lower than what it should, there must be a change made on translateThisMuch const, but I cannot think of anything, any help would be greatly appreciated.
this is the link to the code https://codepen.io/AbramPlus/pen/RwwoPrW
Notice how when it goes from different parts of the scrolling sections to others, there is still some of the other ones left in the view port.
this is the JS code.
const spacer = document.querySelector(".spacer");
const spacerSecond = document.querySelector(".spacerSecond");
const wrapper = document.querySelector(".wrapper");
const windowEffect = document.querySelector(".windowEffect");
const horizontalScrollEnabler = () => {
const scrollFromTop = window.scrollY;
const translateThisMuch = scrollFromTop - spacer.offsetTop;
const spacerHeight = window.innerWidth * 4 ;
const spacerSecondHeight = spacerSecond.offsetHeight;
if (scrollFromTop > spacer.offsetTop && scrollFromTop < spacerSecond.offsetTop && scrollFromTop + window.innerHeight < spacerSecond.offsetTop + spacerSecond.offsetHeight) {
windowEffect.style.position = "fixed";
wrapper.style.transform = `translateX(-${translateThisMuch}px)`;
windowEffect.style.top = "0";
}
if (scrollFromTop < spacer.offsetTop) {
windowEffect.style.position = "absolute";
windowEffect.style.top = "0";
}
if (scrollFromTop > spacer.offsetTop + spacerHeight) {
windowEffect.style.position = "absolute";
windowEffect.style.top = `${window.innerWidth * 4}px`;
}
requestAnimationFrame(horizontalScrollEnabler);
};
document.addEventListener("DOMContentLoaded", horizontalScrollEnabler);
Ok, the problem is when you scroll after the starting point of Horizontal scroll section, upward, since the scrolling can easily bypass the starting point which implements the whole code and translation of X,it may jump 20px, or 10px, or 5 px, the wrapper keeps the Xtrasnlation which it had before scrolling up causing the whole element being left out from being trasnlated by the script, since scrolling up or scrolling down isn't being done 1 pixel at every scroll event. So How do we fix it?
We can extend our starting or ending point by just few hundred pixels so even if we bypass the previous starting or ending points caused by our scrolling down from ending point or scrolling up from our starting point we can still have access to scrolltop - the starter element's offsetTop and define if it is lower than 0 so lets the translation of X of wrapper element to be 0 or if it is bigger than where the end point is it should be equal to -translation of X equal to ending point.
I have this :
<div id="randomp" style="position:absolute;top:3px;left:3px;width:165px;height:29px;background:url(/logo2.png) no-repeat;background-size: 165px;"></div>
I want that the propierty "top" and "left" change every time you enter into the page. I mean that some times it appear on the right top corner, right bottom corner, left top corner and left bottom corner..
Here it is what i have tryied:
http://redzer.com.mx/tabla.html
I would probably start with the div styled as position:fixed and with display:none:
<div id="randomp" style="display:none;position:fixed;width:165px;height:29px;background:url(/logo2.png) no-repeat;background-size: 165px;"></div>
Then use jQuery to determine the position CSS to set and turn on visibility
$(document).ready(function() {
// get jQuery object for the div
var $randomp = $('#randomp');
// determine whether to show top or bottom, left or right
var top = Math.round(Math.random()); // generate 0 or 1 value
if (top === 1) {
$randomp.css('top', '3px');
} else {
$randomp.css('bottom', '3px');
}
var left = Math.round(Math.random());
if (left === 1) {
$randomp.css('left', '3px');
} else {
$randomp.css('right', '3px');
}
// show the div
$randomp.show();
});
Of course, you could also use server-side code to do this, but since you asked specifically about javascript/jquery in your tags, I suggested this solution.
I think i got exactly what you need.
EXAMPLE
With javascript i am generating random numbers for the top and left positioning of your image every time you visit the page.
Right now i set them up to get a random number between 0 and 100 but you can change that to whatever you want.
var random1 = Math.ceil(Math.random() * 100);
var random2 = Math.ceil(Math.random() * 100);
$(document).ready(function () {
$('#randomp').css('top', random1);
$('#randomp').css('left', random2);
});
I've looked everywhere and so far have not found a non-jQuery js to handle this. I would like to avoid using a library for just this one simple task.
I would like to fix three navigation divs ("#header", "#tabs" and "#footer") to viewport left (or alternatively, to the x position of a div "#helper" with "position: fixed; left: 0; top: 0;") -- but not fix y. They can not be vertically fixed.
I've created a working js that forces the divs to reposition based on scrolling, but it's not smooth in the real page (too many dynamic and graphic elements) - I'd like it to either animate smoothly, or mimic fixed-left and not appear to reposition at all.
Anyone who can give pointers or a quick script, or review and modify the script I have made? I've noticed people tend to ask why an obvious solution is not used instead of answering the question... I will be glad to answer, but would prefer help with the actual problem.
Here is a jsFiddle with the problem: http://jsfiddle.net/BMZvt/6/
Thank you for any help!
Smooth animation example:
var box = document.getElementById('box');
var moveTo = function(obj, target) {
// start position
// you should obtain it from obj.style
var cpos = {
x: 0,
y: 0
}
var iv = setInterval(function(){
cpos.x += (target.x - cpos.x) * 0.3; // 0.3 is speed
cpos.y += (target.y - cpos.y) * 0.3; // 0.3 is speed
obj.style.left = Math.floor(cpos.x) + 'px';
obj.style.top = Math.floor(cpos.y) + 'px';
var dist = Math.abs(cpos.y - target.y); // distance (x+y) from destination
dist += Math.abs(cpos.x - target.x); // < 1 = object reached the destination
if(dist < 1) { // here we are checking is box get to the destination
clearInterval(iv);
}
}, 30); // this is also the speed
}
box.onclick = function(){
moveTo(box, {x: 90, y: 75}); // fire this function to move box to specified point
}
Demonstration: http://jsfiddle.net/Qwqf6/5/
Your script is your job, but this is a quick start how to solve animation problem
You can also do some fancy stuff with speed for example use sin(x) to set the speed
Demonstration #2 http://jsfiddle.net/Qwqf6/6/ (very smooth)
Full script here https://gist.github.com/3419179
I don't think there's a straight way to do this...
But here's a way.
First, You need to be able to detect the direction of the scrolling when window.onscroll event happens. You would do this by comparing the current page offsets with the newly acquired page offsets whenever the scroll event happens. (http://stackoverflow.com/questions/1222915/can-one-use-window-onscroll-method-to-include-detection-of-scroll-direction)
Now suppose you know the direction of the scroll, you want to change the styling for the divs depending on the direction of the scroll.
Let FixAtX be the value of the x coordinate that you want to fix your divs at.
Let OriginalY be the y coordinate of the divs.
Also whenever scrolling happens, despite of the direction, you want to remember the pageoffset X and Y. Let's call them OldX and OldY
If scrolling vertically:
Set position value for divs' style to be absolute.
Set top value for divs' style to be OriginalY
Set left value for divs' style to be OldX + FixAtX
If scrolling horizontally:
Set position value for divs' style to be fixed.
set top value for divs' style to be OriginalY - OldY (<- this may be different depending on how the browser computes pageOffset value,)
Set Left value for divs' style to be FixAtX
I think this should work...
Since you are just using browser's rendering for positioning, it should be very smooth!
hope I understood the question correctly.
This is for people who view this post - I wound up going with the solution I initially put together in the jsFiddle that used a simple javascript to mimic fixed x.
The javascript in the first answer was hefty and wound up buggy, and the second answer sounded good but did not work in practice. So, I'm recommending the javascript from the jsFiddle (below) as the best answer to fixed x and fluid y without a javascript library. It's not perfect and has a minimal delay but is the best answer I've found.
function fixLeft() {
function getScrollX() {
var x = 0, y = 0;
if( typeof( window.pageYOffset ) == 'number' ) {
x = window.pageXOffset;
} else if( document.body && ( document.body.scrollLeft) ) {
x = document.body.scrollLeft;
} else if( document.documentElement && ( document.documentElement.scrollLeft) ) {
x = document.documentElement.scrollLeft;
}
return [x];
}
var x = getScrollX();
var x = x[0];
// have to get and add horizontal scroll position px
document.getElementById('header').style.left = x + "px";
document.getElementById('tabs').style.left = x + "px";
document.getElementById('footer').style.left = x + "px";
}
window.onscroll = fixLeft;
What is the best way to restore the scroll position in an HTML document after the screen has been rotated? (This is in a Cocoa Touch UIWebView, but I think it's a problem everywhere.) The default behavior seems to restore the y-offset in pixels, but since the text has been reflowed this is now a different position in the document.
My initial thought is to:
Pepper the document with invisible, uniquely-id'ed elements.
Before rotation, search for the element e whose y-offset is closest to the scroll offset.
After rotation, update the scroll offset to e's new y-offset.
Even if that works, I'd prefer not to insert a bunch of crud into the document. Is there a better way?
Here's a diagram to clarify the problem. Restoring the original y-offset does not produce the intended result because more text fits on a line in landscape mode.
Not pretty but it works. This requires there to be span tags throughout the document text.
// Return the locator ID closest to this height in pixels.
function findClosestLocator(height) {
var allSpans = document.getElementsByTagName("span");
var closestIdx = 0;
var closestDistance = 999999;
for(var i = 0; i < allSpans.length; i++) {
var span = allSpans[i];
var distance = Math.abs(span.offsetTop - height);
if(distance < closestDistance) {
closestIdx = i;
closestDistance = distance;
}
}
return allSpans[closestIdx].id;
}
After rotation, document.getElementById(spanId).offsetTop is the new y-offset, where spanId is the result of findClosestLocator() before rotation.
Conceptually the problem isn't so hard to think about. You have scroll events, rotation events, and variables. I would track the scrollTop position on the document.body DOM node on the scroll event. Reapply it with the orientation event fires.
Something like this perhaps.
// Track position
var pos;
// On scroll update position
document.body.addEventListener("scroll", function() {
pos = document.body.scrollTop;
}, true);
// On rotation apply the scroll position
window.addEventListener("orientationchange", function() {
document.body.scrollTop = pos;
}, true);
I have a #wrapper div and a #grid div nested inside. currently I can scroll around with this function below.
getCursorPos : function(){
// set the empty cursor object
var cursor = {};
//get the offset from the left of the grid container
var grid
//offset loop
$(function getCursorPos(){
grid = $('#grid').offset();
setTimeout(getCursorPos, game.loopSpeed);
});
//continuosly get the position
var that = this;
$(document).mousemove(function(e){
//if game mode is menu exit
if(game.mode === 'menu'){
return;
}
// NOTE: this looks a litle over done but don't remove anything
// its like this because javascript uses floating points
// and so in order to line up to the nearest hunderedth I
// had to make the cursor and div position intergers by
// muliplying by ten. one the two are added I reduced them
// and rounded them.
that.x = Math.round(((e.pageX * 10) - (grid.left * 10)) / 10);
that.y = Math.round(((e.pageY * 10) - (grid.top * 10)) / 10);
});
},
the problem is that the mouse coordinates only update when the mouse moves. is there any way to get the coordinates with out moving the mouse?
You always have the latest up-to-date coordinates of the mouse from the last mouse move, clarify why those are not useful to you.