I have a Javascript file that I am using to try to animate a dropdown menu. I have the "Toggle" function in that file set to run when I click on a certain div. Here's the script I'm using:
var up = true;
function Toggle(x)
{
if (up)
{
for (var i = x.offsetTop; i <= 0; i++)
{
x.style.top = i;
if (i == 0)
{
up = false;
}
}
}
else if (up == false)
{
for (var i = x.offsetTop; i >= -50; i--)
{
x.style.top = i;
if (i == -50)
{
up = true;
}
}
}
}
In the HTML div I want to animate, I have the "onclick" property set to "onclick=Toggle(this)". The first for loop works as it should (it sets the div's top offset to 0). However, the second for loop doesn't set the offsetTop. I know that the for loop is activating because I've tested it and it gives me every integer between 0 and -50. Why isn't it setting the offset position?
1) You must specify a unit to the top ie: x.style.top = i +"px"
2) Your function won't animate instead of you use a setInterval or a setTimeout
Like you asked, an example. I wouldn't do it like this for one of my project, but i kept your function to make you more familiar with the code.
I Used setTimeout instead of setInterval because setInterval must be cleared when not needed and setTimeout is just launched one time :
var Toggle = (function() { // use scope to define up/down
var up = true;
return function(element) {
var top = parseInt(element.style.top, 10); // element.offsetTop ?
if ( !top ) {
top = 0;
}
if (up) {
if (element.offsetTop < 0) { // if we are not at 0 and want to get up
element.style.top = (top+1) + "px";
setTimeout(function() { Toggle(element); }, 10); // recall the function in 10 ms
} else { // we change up value
up = !up;
}
}
else {
if (element.offsetTop > -50) {
element.style.top = (top-1) + "px";
setTimeout(function() { Toggle(element); }, 10); // recall the function in 10 ms
} else {
up=!up;
}
}
}
})();
You'd have to use x.style.top = i + 'px' as top and similar css properties must define the type (px, em, %, etc.) unless they are 0, as this is 0 in any case.
But your script would actually snap the div directly to -50px, as you do not wait between those iteration steps.
I'd recommend to use a library like jQuery to use it's animate() method.
function Toggle(obj) {
$(obj).animate({
top: parseInt($(obj).css('top')) === 0 ? '-50px' : '0px'
})
}
Related
I have two animations which both work, but I'd like to have it so the second animation starts only after the first animation has finished, I tried this with Javascript callbacks but can't seem to get it to work. I'm sure someone can show me how to do this. There must be other ways to do this too? I'd be really interested to find out what they are actually. It's amazing how many different ways there are too do things isn't it.
document.addEventListener("DOMContentLoaded", first, false);
var obj, height, goUp;
function first() {
obj = document.getElementById("thetext");
obj.style.position = "absolute";
obj.style.bottom = "10px";
height = document.body.clientHeight;
goUp = true
second();
}
function second() {
var pos = parseInt(obj.style.bottom, 10);
(goUp) ? pos++ : pos--;
obj.style.bottom = pos + "px";
if (pos < 0) {
goUp = true;
}
if (pos > height) {
goUp = false;
}
if (pos < 0) {
return;
}
setTimeout(second, 10);
}
var objz, width, goRight;
function animatefirst() {
objz = document.getElementById("tues");
objz.style.position = "absolute";
objz.style.left = "10px";
objz.style.bottom = "10px";
width = document.body.clientWidth;
goRight = true;
animatesecond();
}
function animatesecond() {
var position = parseInt(objz.style.left, 10);
(goRight) ? position++ : position--;
objz.style.left = position + "px";
if (position > width) {
goRight = false;
}
if (position < 0) {
goRight = true;
}
if (position < 0) {
return;
}
setTimeout(animatesecond, 10);
}
<body>
<p id="thetext">ANIMATION </p>
<p id="tues"> Tuesday</p>
</body>
I fixed this issue in a simple way, I just put my call to the next function just before the return; which closes the current function. So the call to the next function is not inserted until the part in the code where the first function has finished, to avoid overlapping functions. I'm surprised no one could help with this, but it must be a very busy site :)
if (pos < 0) {
nextfunction();
return;
}
I have been trying to make a simple "smoothscroll" function using location.href that triggers on the mousewheel. The main problem is that the EventListener(wheel..) gets a bunch of inputs over the span of ca. 0,9 seconds which keeps triggering the function. "I only want the function to run once".
In the code below I have tried to remove the eventlistener as soon as the function runs, which actually kinda work, the problem is that I want it to be added again, hence the timed function at the bottom. This also kinda work but I dont want to wait a full second to be able to scroll and if I set it to anything lover the function will run multiple times.
I've also tried doing it with conditions "the commented out true or false variables" which works perfectly aslong as you are only scrolling up and down but you cant scroll twice or down twice.
window.addEventListener('wheel', scrolltest, true);
function scrolltest(event) {
window.removeEventListener('wheel', scrolltest, true);
i = event.deltaY;
console.log(i);
if (webstate == 0) {
if (i < 0 && !upexecuted) {
// upexecuted = true;
location.href = "#forside";
// downexecuted = false;
} else if (i > 0 && !downexecuted) {
// downexecuted = true;
location.href = "#underside";
// upexecuted = false;
}
}
setTimeout(function(){ window.addEventListener('wheel', scrolltest, true); }, 1000);
}
I had hoped there was a way to stop the wheel from constantly produce inputs over atleast 0.9 seconds.
"note: don't know if it can help in some way but when the browser is not clicked (the active window) the wheel will registre only one value a nice 100 for down and -100 for up"
What you're trying to do is called "debouncing" or "throttling". (Those aren't exactly the same thing, but you can look up the difference in case it's going to matter to you.) Functions for this are built into libraries like lodash, but if using a library like that is too non-vanilla for what you have in mind, you can always define your own debounce function: https://www.geeksforgeeks.org/debouncing-in-javascript/
You might also want to look into requestanimationframe.
a different approach
okey after fiddeling with this for just about 2 days i got fustrated and started over. no matter what i did the browsers integrated "glide-scroll" was messing up the event trigger. anyway i decided to animate the scrolling myself and honestly it works better than i had imagined: here is my code if anyone want to do this:
var body = document.getElementsByTagName("BODY")[0];
var p1 = document.getElementById('page1');
var p2 = document.getElementById('page2');
var p3 = document.getElementById('page3');
var p4 = document.getElementById('page4');
var p5 = document.getElementById('page5');
var whatpage = 1;
var snap = 50;
var i = 0;
// this part is really just to read what "page" you are on if you update the site. if you add more pages you should remember to add it here too.
window.onload = setcurrentpage;
function setcurrentpage() {
if (window.pageYOffset == p1.offsetTop) {
whatpage = 1;
} else if (window.pageYOffset == p2.offsetTop) {
whatpage = 2;
} else if (window.pageYOffset == p3.offsetTop) {
whatpage = 3;
} else if (window.pageYOffset == p4.offsetTop) {
whatpage = 4;
} else if (window.pageYOffset == p5.offsetTop) {
whatpage = 5;
}
}
// this code is designet to automaticly work with any "id" you have aslong as you give it a variable called p"number" fx p10 as seen above.
function smoothscroll() {
var whatpagenext = whatpage+1;
var whatpageprev = whatpage-1;
var currentpage = window['p'+whatpage];
var nextpage = window['p'+whatpagenext];
var prevpage = window['p'+whatpageprev];
console.log(currentpage);
if (window.pageYOffset > currentpage.offsetTop + snap && window.pageYOffset < nextpage.offsetTop - snap){
body.style.overflowY = "hidden";
i++
window.scrollTo(0, window.pageYOffset+i);
if (window.pageYOffset <= nextpage.offsetTop + snap && window.pageYOffset >= nextpage.offsetTop - snap) {
i=0;
window.scrollTo(0, nextpage.offsetTop);
whatpage += 1;
body.style.overflowY = "initial";
}
} else if (window.pageYOffset < currentpage.offsetTop - snap && window.pageYOffset > prevpage.offsetTop + snap){
body.style.overflowY = "hidden";
i--
window.scrollTo(0, window.pageYOffset+i);
if (window.pageYOffset >= prevpage.offsetTop - snap && window.pageYOffset <= prevpage.offsetTop + snap) {
i=0;
window.scrollTo(0, prevpage.offsetTop);
whatpage -= 1;
body.style.overflowY = "initial";
}
}
}
to remove the scrollbar completely just add this to your stylesheet:
::-webkit-scrollbar {
width: 0px;
background: transparent;
}
I have a function, to make a div-Box "jump". The function works the first time, but after that I get the error "Uncaught TypeError: jump is not a function" after it gets used once. Can someone please explain why it doesn't work?
already = false;
function jump() {
if (already == false) { //So he can't jump 2 times in a row
try {
clearInterval(t); //<--this is my gravity function, where the div-Box falls down until it hits solid ground
} catch (err) {
console.log("not activated");
}
jump = setInterval("jump2();", 200);
already = true;
}
}
}
anz = 0;
function jump2() {
//Getting coordinates of div-Boy(they work)
var step = 10;
var bottom = getBottom("itBoy");
var right = getRight("itBoy");
var top = getTop("itBoy");
var left = getLeft("itBoy");
//lets see if he hits an object
if (anz <= 100) { //<-- anz = so he cant jump higher than 100 px
if (top - step >= 0) {
var a = hittest("itBoy", "up", 10); //if div wont hit a solid object --> return -1 | else return coordinates of bordes which collide (this function works too)
if (a == -1) {
anz += step;
document.getElementById("itBoy").style.top = (top -= step) + "px";
} else {
document.getElementById(itBoy).style.top = a + "px";
clearInterval(jump); // div stops moving upwards
t = setInterval("move('down');", 50); //gravity gets Activated again
}
}
} else {
clearInterval(jump);
t = setInterval("move('down');", 50);
}
}
It's because, you're overriding the jump:
function jump(){
// ...
jump = setInterval("jump2();",200);
// ^^ give it a different name
Also, a good approach to use function inside setInterval like:
setInterval(jump2, 200); // faster
Theres some wierd behaviour when playing with Paperjs, i was trying to curve a line up with 7 points separately - which works fine once, but when trying to make the link overshoot and return to 3 different points (to create a bounce effect) doesn't seem to play ball. On the second if statement, the 'counter' variable doesnt seem to increase instead of decrease, '+ steps' instead of '- steps'.
Maybe i'm not using if statements properly in this case, or paperjs has some strange behaviour?
Heres the codepen for it in full, click above the blue line to trigger it off. . Following is one setInterval for one of the points of the segment.
var seg6first = true;
var seg6sec = false;
var seg6thir = false;
setInterval(function() {
if (seg6first == true) {
counter = counter - steps;
if (counter >= 230) {
path.segments[6].point.y = counter;
path.smooth(); }
else {
seg6first = false;
seg6sec = true;
}
}
if (seg6sec == true) {
counter = counter + steps;
if (counter <= 260) {
path.segments[6].point.y = counter;
path.smooth();}
else {
seg6sec = false;
seg6thir = true;
}
}
if (seg6sec == true) {
counter = counter - steps;
if (counter >= 250) {
path.segments[6].point.y = counter;
path.smooth(); }
else {
seg6thir = false;
}
}
}, mintiming);
Thanks!
Rather than manually building your bounce effect, you can use an animation library like GSAP.
It has a lot of features that will make your task easier (see easing documentation).
Here is an example of what you are trying to do (click on the canvas to animate the line).
html,
body {
margin: 0;
overflow: hidden;
height: 100%;
}
canvas[resize] {
width: 100%;
height: 100%;
}
<canvas id="canvas" resize></canvas>
<script src="https://cdnjs.cloudflare.com/ajax/libs/gsap/2.0.2/TweenMax.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/paper.js/0.11.8/paper-full.min.js"></script>
<script type="text/paperscript" canvas="canvas">
// user defined constants
var SEGMENTS_COUNT = 6;
var CURVE_HEIGHT = 80;
var ANIMATION_DURATION = 2;
// init path
var path = new Path({
fillColor: 'orange',
selected: true
});
// add points
for (var i = 0; i <= SEGMENTS_COUNT; i++) {
path.add([view.bounds.width * i / SEGMENTS_COUNT, view.center.y]);
}
// on mouse down...
function onMouseDown() {
// ...animate points
for (var i = 0, l = path.segments.length; i < l; i++) {
// get a reference to the point
var point = path.segments[i].point;
// calculate offset using sine function to form a curve
var offset = CURVE_HEIGHT * Math.sin(point.x * Math.PI / view.bounds.width);
// register animation
TweenLite.fromTo(
// target
point,
// duration
ANIMATION_DURATION,
// initial value
{ y: view.center.y },
{
// final value
y: view.center.y - offset,
// easing
ease: Elastic.easeOut.config(1, 0.3),
// on update...
onUpdate: function() {
// ...smooth the path
path.smooth();
}
}
);
}
}
</script>
Im having a very strange bug. Im trying to limit the amount of scroll calls within a jquery mousewheel function. I have set a timer to limit the calls but it doesnt seem to call the function scrollLeft. However, it works if its not wrapped in any timer. Is this some kind of native JS bug? or has anyone found a workaround for it?
$(document).ready(function() {
var scrpos=0;
var limitTimer;
var did= true;
$('html, body, *').bind('mousewheel', function(event,delta){
var BODY= this;
if (did){
did =false;
if (delta > 0) {
if (scrpos >= $(document).width() - $(window).width()){
}else{
scrpos += 100;
}
} else {
if (scrpos !== 0){
scrpos -= 100;
}
}
BODY.scrollLeft = scrpos;
console.log(scrpos);
var limitTimer = setTimeout(function(){
did=true;
clearTimeout(limitTimer);
}, 150);
}
//Works here when outside the call
//BODY.scrollLeft = scrpos;
});
});