Whats wrong with my JavaScript animation? - javascript

So i have this web-page to design and i want an image of the moon to rise-up from bottom of the screen to top. This is the HTML :
<body>
<div id="Moon" onload="Moon()"></div>
</body>
CSS :
#Moon{
width: 150px;
height: 150px;
left: 50px;
top: 600px;
background: transparent url(../Img/Moon.SVG) no-repeat ;
position: absolute;
}
and JavaScript for animation :
function Moon(){
var Moon=document.getElementById("Moon");
var yposition=Moon.style.top;
var id = setInterval(frame, 10);
function frame(){
if (Moon.style.top > 100) {
yposition--;
Moon.style.top = yposition + 'px';
} else {
clearInterval(id);
}
frame();
}
}
but for some reasons the image of moon stays at the bottom of the page and doesn't move at all. any ideas?

Try like this.
you need to calculate top offset of the div using moon.offsetTop
and a div does not have a onload event so you will have to call your Moon() function either from script or from body onload event
function Moon(){
var moon=document.getElementById("Moon");
var yposition= parseInt(moon.offsetTop) ;
var id = setInterval(frame, 10);
function frame()
{
if (moon.offsetTop > 10) {
yposition--;
document.getElementById("Moon").style.top = yposition + 'px';
} else {
clearInterval(id);
}
}
}
#Moon{
width: 300px;
height: 250px;
left: 50px;
top: 600px;
background: transparent url("https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcQh7mGmBMJ--wS711QkCEPHHS56jV15VmESttDbVLZPSI_FsMAyTQ") no-repeat ;
position: absolute;
}
<body onload="Moon()">
<div id="Moon"></div>
</body>

Related

how to make a box reach the edge of a bigger box

javascript beginner here! so i'm trying to do a box(that is inside a larger box) move from the top to the edge of the box. Here's the code:
var boxcont = document.getElementById("boxcont");
var boxbtn = document.getElementById("boxbtn");
boxbtn.addEventListener("click", function() {
var loc = 0;
var timebox = setInterval(boxmove, 5);
function boxmove() {
if (loc == 320) {
clearInterval(timebox);
} else {
loc++;
boxcont.style.top = loc + "px";
boxcont.style.left = loc + "px";
}
}
});
#movebox {
width: 300px;
height: 350px;
background-color: grey;
}
#boxcont {
width: 30px;
height: 30px;
background-color: indianred;
position: relative;
}
<div id="movebox">
<div id="boxcont"></div>
</div>
<button id="boxbtn">Move the box</button>
The problem is that the small box doesn't exactly ends up at the edge, it goes more to the right. I tried doing
boxcont.style.left = (loc - 0.5) + "px";
but doesn't work. pretty sure the solution is simple but as a newbie here it's confusing me :p. Oh and i also tried doing ++ to the 0.5 and Number(0.5) so it reads it as a decimal but still doesn't work!
the big gray box is not set to the correct height and width that corresponds with the small red box's movement. You have it going down 1 and to the right 1 every 5 however, your actually going across a rectangle, not a square. set your width and height the same for the gray box and slightly adjust the stopping point to a little bit less.
var boxcont = document.getElementById("boxcont");
var boxbtn = document.getElementById("boxbtn");
boxbtn.addEventListener("click", function() {
var loc = 0;
var timebox = setInterval(boxmove, 5); // every five milliseconds
function boxmove() {
if (loc == 290) {
clearInterval(timebox);
} else {
loc++;
boxcont.style.top = loc + "px";
boxcont.style.left = loc + "px";
}
}
});
#movebox {
width: 300px;
height: 350px;
background-color: grey;
}
#boxcont {
width: 30px;
height: 30px;
background-color: indianred;
position: relative;
}
<div id="movebox" style = "height: 320px; width: 320px">
<div id="boxcont" ></div>
</div>
<button id="boxbtn">Move the box</button>
if (loc == 270) {
instead of
if (loc == 320) {
Gets you there.
300px is the width of the containing div and the moving div is 30px wide so 300-30=270px
var boxcont = document.getElementById("boxcont");
var boxbtn = document.getElementById("boxbtn");
boxbtn.addEventListener("click", function() {
var loc = 0;
var timebox = setInterval(boxmove, 5);
function boxmove() {
if (loc == 270) {
clearInterval(timebox);
} else {
loc++;
boxcont.style.top = loc + "px";
boxcont.style.left = loc + "px";
}
}
});
#movebox {
width: 300px;
height: 350px;
background-color: grey;
}
#boxcont {
width: 30px;
height: 30px;
background-color: indianred;
position: relative;
}
<div id="movebox">
<div id="boxcont"></div>
</div>
<button id="boxbtn">Move the box</button>

use jQuery setInterval to decreases the width of element but from only one side (left or right )

here are my codes for decreasing the width of an selected element(class = "life_bar"), but as my attached pictures show, I want it to decrease its width from left or right( let's do left as example), but it always goes from both side, what should I do?
here are jQuery codes
$(function () {
var timmer;
gocount();
function gocount(){
timmer = setInterval(function () {
var life_bar_width = $(".life_bar").width();
life_bar_width -= 100;
$(".life_bar").css( {width: life_bar_width,
left: '-50px'})
},1000);
}
});
here are css codes
.life_bar{
width: 500px;
height: 10px;
background: crimson;
margin: 100px auto;
}
here are html codes
<body>
<div class="life_bar"></div>
</body>
using translate negative on X every interval tick:
$(function () {
var timmer;
gocount();
let counter = 1
function gocount(){
timmer = setInterval(function () {
var life_bar_width = $(".life_bar").width();
life_bar_width -= 100;
$(".life_bar").css({
width: life_bar_width,
left: '-50px',
transform: `translate(${-50*counter}px)`
})
counter++
},1000);
}
});
.life_bar{
width: 500px;
height: 10px;
background: crimson;
margin: 100px auto;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="life_bar"></div>

animated loads in wrong spot

I have a div that animates up and down which works fine. The issue I'm getting is that every time the page loads the div starts at the very top of the page and then jumps down to where it needs to be after the animation starts.
<body id="body">
<div id="square"></div>
</body>
#body {
background: #000;
}
#square {
background-color: #fff;
margin: 0 auto;
position: relative;
width: 100px;
height: 100px;
}
var box = document.getElementById('square');
TOP = (window.innerHeight - box.offsetHeight)/2;
box.style.top = TOP;
var down = setInterval(animateDown, 15);
var up;
function animateDown()
{
TOP += 3;
box.style.top = TOP + 'px';
if(TOP > 900){
clearInterval(down);
up = setInterval(animateUp, 15);
}
}
function animateUp()
{
TOP -= 3;
box.style.top = TOP + 'px';
if(TOP <= (window.innerHeight - box.offsetHeight)/2){
clearInterval(up);
down = setInterval(animateDown, 15);
}
}
Here is a link to the jsfiddle as well >> https://jsfiddle.net/xgilmore/pLbgvc3L/
thanks in advance
This is sort of a work around, but you can start the box off as hidden, and then once you start animating, set it visible. https://jsfiddle.net/pLbgvc3L/1/
function animateDown()
{
box.style.visibility = 'visible';
#square {
background-color: #fff;
//margin: 0 auto;
position: relative;
width: 100px;
height: 100px;
top: 20%;
visibility: hidden;
}
Oh sorry, I actually know what is going on, it just took a second look to figure it out. top: 20% doesn't do anything because percentages only work if the parent element (body) has an explicit height. Like so https://jsfiddle.net/pLbgvc3L/2/

jitter when using jquery to alter background-position

Here's the jsfiddle.
It's the interface to cropping an image. As you can see the selection div takes the same background image and positions it to the negative of the top and left attributes of the selection div. In theory this should give a perfect overlap, but there's a jitter as you move the selection div around, and I can't seem to figure out what is causing it.
html
<div id="main">
<div id="selection"></div>
</div>
css
#main {
width: 600px;
height: 450px;
position: relative;
background: url("http://cdn-2.historyguy.com/celebrity_history/Scarlett_Johansson.jpg");
background-size: contain;
}
#selection {
width: 100px;
height: 100px;
position: absolute;
background: url("http://cdn-2.historyguy.com/celebrity_history/Scarlett_Johansson.jpg");
border: 1px dotted white;
background-size: 600px 450px;
}
jquery
$(document).ready(function () {
var move = false;
var offset = [];
var selection = null;
$("#selection").mousedown(function (e) {
move = true;
selection = $(this);
offset = [e.pageX - selection.offset().left, e.pageY - selection.offset().top];
});
$("#selection").mousemove(function (e) {
if (move == true) {
selection.css("left", e.pageX - offset[0]);
selection.css("top", e.pageY - offset[1]);
selection.css("background-position", (((-selection.position().left) - 1) + "px " + ((-selection.position().top ) - 1) + "px"));
}
});
$("#selection").mouseup(function (e) {
move = false;
});
})
It would appear that there is a value of 5 offset that needs to be added to ensure seamlessness
DEMO http://jsfiddle.net/nzx0fcp5/2/
offset = [e.pageX - selection.offset().left + 5, e.pageY - selection.offset().top + 5];
So, while experimenting I discovered that this was only a problem at certain sizes of the image. At the original size it is no problem, neither at half nor a quarter of this size. It wasn't simply a matter of keeping the image in proportion not having the image square or using even pixel sizes. I'm assuming this had something to do with partial pixel sizes, but I'm not sure, and I couldn't see any way to work around this, at least none that seemed worth the effort.
So while checking out the code of other croppers I took a look at POF's image cropper, they seem to have got round the problem by not using the background-position property at all (I'm not sure if it's plugin or they coded it themselves). They just set the image down and then used a transparent selection div with 4 divs stuck to each edge for the shading. So there's no pixel crunching on the fly at all. I like the simplicity and lightweight nature of this design and knocked up a version myself in jsfiddle to see if I could get it to work well.
new jitter free jsfiddle with no pixel crunching
I liked the solution for the preview box as well.
html
<body>
<div id="main">
<img src="http://flavorwire.files.wordpress.com/2012/01/scarlett_johansson.jpg" />
<div id="upperShade" class="shade" > </div>
<div id="leftShade" class="shade" > </div>
<div id="selection"></div>
<div id="rightShade" class="shade"></div>
<div id="lowerShade" class="shade" ></div>
</div>
</body>
css
#main {
position:relative;
width: 450px;
height: 600px;
}
#selection {
width: 148px;
height: 148px;
position: absolute;
border: 1px dotted white;
top: 0px;
left: 0px;
z-index: 1;
}
.shade {
background-color: black;
opacity: 0.5;
position: absolute;
}
#upperShade {
top: 0px;
left: 0px;
width: 600px;
}
#leftShade {
left: 0px;
top: 0px;
height: 150px;
width: auto;
}
#rightShade {
left: 150px;
top: 0px;
height: 150px;
width: 450px;
}
#lowerShade {
left:0px;
top: 150px;
width: 600px;
height: 300px;
}
jquery
$(document).ready(function () {
var move = false;
var offset = [];
var selection = null;
$("#selection").mousedown(function (e) {
move = true;
selection = $(this);
offset = [e.pageX - selection.offset().left, e.pageY - selection.offset().top];
});
$("#selection").mousemove(function (e) {
if (move == true) {
selection.css("left", e.pageX - offset[0]);
selection.css("top", e.pageY - offset[1]);
setShade();
}
});
function setShade() {
$("#upperShade").css("height", selection.position().top);
$("#lowerShade").css("height", 600 - (selection.position().top + 150));
$("#lowerShade").css("top", selection.position().top + 150);
$("#leftShade").css("top", selection.position().top);
$("#leftShade").css("width", selection.position().left);
$("#rightShade").css("top", selection.position().top);
$("#rightShade").css("left", selection.position().left + 150);
$("#rightShade").css("width", 450 - selection.position().left);
}
$("#selection").mouseup(function (e) {
move = false;
});
});

jquery slider responsive problems

I am a beginner with jQuery and I was trying to make an slider responsive and is working but I have some bugs that I want to fix, first of all when is passing to the next picture some times it just turn white and it does not working any more, and second some times it start to go faster and faster.
Any suggestions?
.mascara
{ width: 100%; height: 100%;
overflow: hidden;
}
.carrusel{ position: relative; width: 100%; height: 100%; }
.carrusel li{ width:25%; height: 100%; float: left; background-repeat: no-repeat; background-position: center; background-size: cover; }
<script src="jquery-2.0.3.min.js"></script>
<script>
var cantidadFotos = $('.carrusel li').size();
var incremento = $('.mascara').width();
var limite = (cantidadFotos-1) * incremento;
var velocidad = 550;
$('.carrusel').css('width', (cantidadFotos*100)+"%");
$('.carrusel li').css('width', incremento+"px");
var posX = 0;
resize();
function resize()
{
$(window).resize(function () {
incremento = $('.mascara').width();
$('.carrusel li').css('width', incremento+"px");
posX = -(incremento * imagenes);
$('.carrusel').css('left', posX+"px");
});
setInterval(function(){ nextFoto(); }, 3000);}
var imagenes = 0;
function nextFoto(){
imagenes++;
posX+= -incremento;
if (posX<-limite){
posX=0;
imagenes = 0;
$('.carrusel').css({ left: posX });
}
$('.carrusel').animate({ left: posX},350);
// $('.carrusel').css({ left: posX});
return false;
}
</script>
If you want to remove the blank page when sliding, change to this:
In .carrusel
Change:
position: relative;
To:
position: absolute;
And to make it faster, change:
setInterval(function () {
nextFoto();
}, 3000);
To
setInterval(function () {
nextFoto();
}, 1000);
Change according to your needs to make it faster!
Demo

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