javascript: time until page load - javascript

i am writing a animation with javascript and want to print to user loading time until all images loaded.
images set in html as: <img src="" />
are there javascript code to know when all page loaded?
i.e time until onLoad() event called

You might be able to do something like this at the bottom of the page
<span id="imgsMsg"></span>
<script type="text/javascript">
var imgs = document.images;
var len = imgs.length;
var percent = 100;
var count=0;
var messagecontainer = document.getElementById("imgsMsg");
for (var i=0;i<len;i++) {
imgs[i].onload=function() {
count++;
messagecontainer = (percent - Math.floor((100/len)*count))+"% loaded"; // hope my math is correct ;)
}
}
</script>
</body>

The best you can probably do is to track the number of images that have been loaded, and divide that into the total number of images remaining. Something like this:
var total_loaded = 0;
$('img').load(function()
{
total_loaded += 1;
var load_progress = total_loaded / $('img').length;
// you can now use load_progress to show the user a rough progress animation
} );
If you want a "time remaining" display, you'll need to fake it. You could track the total time elapsed and compare that to the load_progress variable to get the remaining time, for example.

This isn't hard to do, with $(window).load:
var readytime = new Date().getTime();
$(window).load(function() {
var loadingtime = (new Date().getTime() - readytime) / 1000; // in seconds
$('#yourTimingField').text(loadingtime + ' seconds');
});
This measures the amount of time between the this part of the script and the loading of all subelements.

Related

jQuery fade in box with unique content

I am making an info screen, and for that, it needs to show reviews from their customers pulled from Trustpilot.
I got the reviews and everything formatted in HTML showing the 20 latest, but I want to present it very sweet. I am not a JavaScript guru, but I thought i would do it using jQuery and its fadein function.
What is want, is have 20 unique divs fading in with X milliseconds difference popping randomly up. By unique I mean, that each div must have unique content. And by randomly popping up, I mean that if box 1 spawns first, then the next should be 5, then 14 etc, and then another cycle the next time around.
Just like what I made here;
$(function() {
var box = $('.box');
var delay = 100;
for (i = 0; i < 30; i++) {
setTimeout(function() {
var new_box = box.clone();
$('.container').append(new_box);
new_box.fadeIn();
}, delay);
delay += 500; // Delay the next box by an extra 500ms
}
});
http://jsfiddle.net/CCawh/5/
Is this even possible, and how would this be done?
I am very new to JavaScript, so please bear with me if I ask to much
Thanks in advance.
EDIT:
The HTML i want to spawn will all be wrapped in divs, so it would go like this;
<div id="one">content</div>
<div id="two">content</div>
<div id="three">content</div>
<div id="four">content</div>
etc.
Made up a nice function for you. I believe this may be what you are looking for
Here's a rundown of how it works :
Populate an array with numbers randomly generated 1-10 in this case.
Run through that array with a set interval, and when everything has
been added stop the interval
pretty straightforward from there. Set the visibility etc. You should be able to change up the function to dynamically add HTML elements and what-not, but just giving you something to start with.
var usedNum = [];
var i, j, y;
i = 0;
for(y = 0; y < 10; y++){
var x = Math.floor((Math.random() * 10) + 1);
if(!isUsed(x)) usedNum.push(x);
else y--;
}
var showInterval = setInterval ( function(){
if(i == 10){
clearInterval(showInterval);
}
$(".container div[data-line='" + usedNum[i] + "']").css({opacity: 0.0, visibility: "visible"}).animate({opacity: 1.0});
i++;
}, 500);
function isUsed(num) {
var used = false;
for(j = 0; j < usedNum.length; j++){
if(usedNum[j] == num){
used = true;
}
}
return used;
}
Demo fiddle : http://jsfiddle.net/xS39F/3/
Edit:
You can also mess around with the speed of the animation. In this demo (http://jsfiddle.net/adjit/XYU34/1/) I set the speed to 1000 so the next element starts fading in before the last element was done fading in. Makes it look a little smoother.
Instead of using a for loop and setTimeout, would setInterval work better for what you need? Some HTML might help better understand what you're trying to achieve.
$(function() {
var box = $('.box');
var delay = 100;
var interval = setInterval(function() {
var new_box = box.clone();
$('.container').append(new_box);
new_box.fadeIn();
}, delay);
delay += 500; // Delay the next box by an extra 500ms
}, delay);
});

Simple JavaScript image rotator

I have a simple image rotator on a website consisting of 4 images that have to appear for a few seconds before showing the next one. It seems to work on its first cycle but then when it gets back to the first image it doesn't show that one but works again from the second image and so on always missing that image on every cycle.
The function is called using onLoad EH in the body. In the body there is an img with my first image inside it. I'm a noob so please be gentle if I've missed anything out.
Here's what I have...
<body onLoad="sunSlideShow()">
<img src="IMAGES/slider1.gif" alt="slide-show" id="mySlider" width="900">
<body>
var quotes = new Array ("slider2.gif", "slider3.gif" ,"slider4.gif", "slider1.gif");
var i = 0
function sunSlideShow()
{
document.getElementById("mySlider").src = ( "IMAGES/" + quotes[i] );
if (i<4)
{
i++;
}
else
i = 1;
setTimeout("sunSlideShow()", 3000);
}
sunSlideShow()
Change it to this:
else
i = 0;
setTimeout("sunSlideShow()", 3000);
Further to my other answer (which was wrong!)... Try this:
http://jsfiddle.net/pq6Gm/13/
<script src="//ajax.googleapis.com/ajax/libs/jquery/2.1.0/jquery.min.js"></script>
<script type="text/javascript">
$(document).ready(function(){
setInterval(sunSlideShow,3000);
});
var quotes = [
"http://static.guim.co.uk/sys-images/Guardian/Pix/pictures/2007/07/11/sun128.jpg",
"http://icons.iconarchive.com/icons/robinweatherall/seasonal/128/sun-icon.png",
"http://www.astronomytoday.com/images/sun3.gif",
"http://mariusbancila.ro/blog/wp-content/uploads/2011/08/sun.png"
];
var i = 0;
function sunSlideShow() {
document.getElementById("mySlider").src = quotes[i];
if (i < (quotes.length-1))
{
i++;
}
else
{
i = 0;
}
}
</script>
<body>
<img src="http://mariusbancila.ro/blog/wp-content/uploads/2011/08/sun.png" id="mySlider"/>
</body>
==================================================================
EDIT: This is wrong... please find my other answer on this page.
==================================================================
To start with, I wouldn't use ... you're better off starting the script with jquery once the page is loaded.
Add this to your head section:
<script type="text/javascript">
$(function () {
sunSlideShow();
}
</script>
That will fire the sunSlideShow function once the page is loaded.
Then, you're starting your slideshow with var i = 0... but when you've got to the fourth image, you're setting it to 1?
I would be tempted to use a while loop to achieve what you want.
Something like this:
<script type="text/javascript">
$(function () {
sunSlideShow();
}
var quotes = new Array ("slider2.gif", "slider3.gif" ,"slider4.gif", "slider1.gif");
var i = 0;
function sunSlideShow(){
while (i<4)
{
document.getElementById("mySlider").src = ( "IMAGES/" + quotes[i] );
if (i<4)
{
i++;
}
else
{
i = 0;
}
sleep(3000);
}
}
function sleep(miliseconds){
var currentTime = new Date().getTime();
while (currentTime + miliseconds >= new Date().getTime()){}
}
</script>
This script hasn't been tested... but it should start the sunSlideShow function once the page has loaded and then change the image every 3 seconds.
I too searched the web trying to find a general solution to the problem of rotating an image about its center. I came up with my own solution which works perfectly. The basic concept is simple: rotate the entire context by the desired angle (here called 'tilt'); calculate the image's coordinates in the NEW coordinate system; draw the image; lastly, rotate the context back to its original position. Here's the code:
var xp = rocketX * Math.cos(tilt) - rocketY * Math.sin(tilt);
var yp = rocketX * Math.sin(tilt) + rocketY * Math.cos(tilt);
var a = rocketX - xp;
var c = Math.sqrt(a*a + (rocketY-yp)*(rocketY-yp));
var beta = Math.acos(a/c);
var ap = c * Math.cos(tilt + beta);
var bp = c * Math.sin(tilt + beta);
var newX = rocketX + ap;
var newY = rocketY - bp;
context.rotate(tilt);
context.drawImage(littleRocketImage, newX-9, newY-40);
context.rotate(-tilt);
In the penultimate line, the constants '9' and '40' are half the size of the image; this insures that the rotated image is placed such that its center coincides with the center of the original image.
One warning: I use this only for first quadrant rotations; you'll have to put in the standard tests for the other quadrants that change the signs of the components.
Update: 2021
You can use the light-weight library Ad-rotator.js to setup simple Ad-rotation like this -
<script src="https://cdn.jsdelivr.net/npm/ad-rotator"></script>
<script>
const instance = rotator(
document.getElementById('myelement'), // a DOM element
[ // array of ads
{ url: 'https://site1.com', img: 'https://example/picture1.jpg' },
{ url: 'https://site2.com', img: 'https://example/picture1/picture2.jpg'},
// ...
]
);
</script>
<body onLoad="instance.start()">
<div id="myelement"></div>
<body>
Reference Tutorial

Using JQuery to create animation frames from PSD layers

I have a PSD file with a bunch of layers that are frames for an animation. How can I create an animation from this using JQuery/JavaScript?
Will I have to save each layer as a separate image, is there a way to have the one image with multiple layers animated? To clarify, I don't want the actual image to move, I just want different layers to be displayed as if they were frames of an animation. What's the standard way this is done with JavaScript?
Thanks!
Here is a fiddle that demonstrates the javascript timer + individual images approach.
Fiddle: http://jsfiddle.net/ZVFu8/2/
The basic idea is to create an array with the names of your images.
var img_name_arr = [];
var img_name_root = "anim-";
var img_name_ext = ".gif";
var num_images = 12;
// init arr of img names assuming frames are named [root]+i+[extension]
for (i = 0; i<=num_images; i++) {
img_name_arr.push(img_name_root + i + img_name_ext);
}
For the animation, use setInterval(). In javascript, an interval executes periodically. You specify the code to execute and the interval at which the code should be run (in milliseconds).
Every time your interval is called, you can display a new image by setting the "src" attribute of the image tag to the next index in the image_name array.
// Create an interval, and save a handle to the interval so it can be stopped later
anim_interval = setInterval(function() {
$("#player").attr("src", s + img_name_arr[(anim_frame++ % num_images)+1] );
}, frame_interval);
Depending on how long your animation is and how large each image file is, it might be necessary to optimize this by pre-loading these images. Before the animation starts, you could create an img tag for each image and hide it. Then, instead of altering the "src" attribute to change the image, you would actually hide the current image and un-hide the next image in the previous image's place.
Here is the full code if you wish to run this locally:
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<a id="anim_control" href="">Start</a>
<img id="player" src="" />
<script>
var s = "http://" + atob("YmVucmlkb3V0LmNvbQ==") + "/";
var img_name_arr = [];
var img_name_root = "anim-";
var img_name_ext = ".gif";
var num_images = 12;
var framerate = 1; // Desired frames per second
var frame_interval = 1000/framerate;
$(function(){
// Document is ready
// init arr of img names
for (i = 0; i <= num_images; i++) {
img_name_arr.push(img_name_root + i + img_name_ext);
}
var anim_interval = null;
var playing = false;
var anim_frame = 0;
// Define an interval that will execute every [frame_interval] milliseconds
$("#anim_control").on("click", function(e) {
e.preventDefault();
if (playing == true) {
playing = false;
$(this).html("Start");
clearInterval(anim_interval);
} else {
playing = true;
$(this).html("Stop");
anim_interval = setInterval(function() {
//console.log(s + img_name_arr[(anim_frame++ % num_images)+1]);
$("#player").attr("src", s + img_name_arr[(anim_frame++ % num_images)+1] );
}, frame_interval);
}
});
});
</script>
<style>
#player {
width: 320px;
height: 240px;
border: 1px solid #000;
}
</style>

multiple animations like flash

The below code (I just gave a snippet of working code) animates a few images based on time. Something like a Flash animation where at certain times images start to move at certain times or frame count. My question is , is there a better way to do this ? I know I can use something other than setInterval . I am calculating the elapsed time and setting off images based on the time interval.
It is the ClassLoadImages.prototype.m_draw which is the issue.
function doGameLoop() {
ctx.clearRect(0,0,600,400);
now = new Date();
totalSeconds = (now - start) / 1000;
last = now;
ctx.fillText("totalSeconds=" +totalSeconds ,10,100);
if (totalSeconds>2 && totalSeconds<6)
{
img2.m_draw(130);
}
if (totalSeconds>4 && totalSeconds<8)
{
img3.m_draw2(230);
}
if (totalSeconds>10){
start = new Date();//start again
}
img.m_draw(30);
// fi++;
}
var img= new ClassLoadImages(30,30);
var img2= new ClassLoadImages(30,30);
var img3= new ClassLoadImages(30,30);
</script>
If you want something like flash movieclips, check out SpriteClip on github. https://github.com/wolthers/SpriteClip.js

JavaScript Photo Slider

I'm working on making a JS script that will go in the header div and display a few pictures. I looked into JQuery Cycle, but it was out of my league. The code I wrote below freezes the browser, should I be using the for loop with the timer var?
<script type="text/JavaScript" language="JavaScript">
var timer;
for (timer = 0; timer < 11; timer++) {
if (timer = 0) {
document.write('<img src="images/one.png">');
}
if (timer = 5) {
document.write('<img src="images/two.png">');
}
if (timer = 10) {
document.write('<img src="images/three.png">');
}
}
</script>
Thanks!
Assuming you want a script to rotate images and not just write them to the page as your code will do, you can use something like this:
<!DOCTYPE html>
<html>
<head>
<title></title>
</head>
<body>
<div id="target"></div>
<script>
var ary = ["images/one.png","images/two.png","images/three.png"];
var target = document.getElementById("target");
setInterval(function(){
target.innerHTML = "<img src=\""+ary[0]+"\" />";
ary.push(ary.shift());
},2000);
</script>
</body>
</html>
Of course the above code has no effects (like fading) which jQuery will give yous, but it also doesn't require loading the entire jQuery library for something so basic.
How about just running the script after the page loads?
<script>
// in <head> //
function load() {
var headDiv = document.getElementById("head");
var images = ["images/one.png", "images/two.png"];
for(var i = 0; i<images.length; i++) {
image = document.createElement("img");
image.src = images[i];
headDiv.appendChild(image);
}
}
</script>
Then use <body onload="load();"> to run the script.
Edit
To add in a delay loading images, I rewrote the code:
<script>
// in <head> //
var displayOnLoad = true; // Set to true to load the first image when the script runs, otherwise set to false to delay before loading the first image
var delay = 2.5; // seconds to delay between loading images
function loadImage(url) {
image = document.createElement("img");
image.src = images[i];
headDiv.appendChild(image);
}
function load() {
var headDiv = document.getElementById("head");
var images = ["images/one.png", "images/two.png"];
for(var i = 0; i<images.length; i++) {
setTimeout(loadImage(images[i]), (i+displayOnLoad)*(delay*1000));
}
}
</script>
Set displayOnLoad = false; if you want to wait the specified delay before loading the first image. The delay is set in seconds. I recommend waiting over a single second between images, as they may take some time to download (depending on the user's internet speed).
As with the first snippet, I haven't tested the code, so please tell me if an error occurs, and I will take a look.
Since you used the jquery tag on your question, I assume you are OK with using jQuery. In which case, you can do something like this:
In your static HTML, include the img tag and set its id to something (in my example, it's set to myImg) and set its src attribute to the first image, e.g.:
<img id="myImg" src="images/one.png">
Next, use jQuery to delay execution of your script until the page has finished loading, then use setTimeout to create a further delay so that the user can actually spend a few seconds looking at the image before it changes:
<script>
var imgTimeoutMsecs = 5000; // Five seconds between image cycles
$(function() {
// Document is ready
setTimeout(function() {
// We will get here after the first timer expires.
// Change the image src property of the existing img element.
$("#myImg").prop("src", "images/two.png");
setTimeout(function() {
// We will get here after the second, nested, timer expires.
// Again, change the image src property of the existing img element.
$("#myImg").prop("src", "images/three.png");
}, imgTimeoutMsecs);
}, imgTimeoutMsecs);
});
</script>
Of course, that approach doesn't scale very well, so if you are using more than three images total, you want to modify the approach to something like this:
var imgTimeoutMsecs = 5000; // Five seconds between image cycles
// Array of img src attributes.
var images = [
"images/one.png",
"images/two.png",
"images/three.png",
"images/four.png",
"images/five.png",
];
// Index into images array.
var iCurrentImage = 0;
function cycleImage() {
// Increment to the next image, or wrap around.
if (iCurrentImage >= images.length) {
iCurrentImage = 0;
}
else {
iCurrentImage += 1;
}
$("#myImg").prop("src", images[iCurrentImage]);
// Reset the timer.
setTimeout(cycleImages, imgTimeoutMsecs);
}
$(function() {
// Document is ready.
// Cycle images for as long as the page is loaded.
setTimeout(cycleImages, imgTimeoutMsecs);
});
There are many improvements that can be made to that example. For instance, you could slightly simplify this code by using setInterval instead of setTimer.
The code you've provided simply iterates through the for loop, writing the images to the browser as it does so. I suggest you take a look at JavaScript setTimeout function.
JS Timing

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