I want to print a different content from my web page that includes an image. So is my JavaScript code:
function print() {
var w = window.open();
w.document.write(....);
// time for rendering images
setTimeout(function () { w.print(); w.close();},10);
}
Google Chrome shows a new tab, with no print dialog. When I exit the tab and return it, the print dialog shows!
When I take out the 10 ms timeout, it not shows my image (there is no time for rendering the image), but the dialog shows instantly.
Maybe, someone will tell me: Creates HTML using DOM functions like createElement and appendChild. So you don't need rendering time and it is neater.
Therefore I did an alternative with whole HTML content created from scratch
I've used the src dinamic assigment for my image
ele.setAttribute("src","LogoUp.png"); // ele is an image element
instead using a static HTML with same src value
<img id="header" style="margin-left: auto;
margin-right:auto;" src="LogoUp.png" >
PS: My Chrome is updated (v.63)
Now there is no need for rendering time and I can extract the setTimeout function call, however the image is not loading. It's very weird. I saw it in the Chrome DevTools, the official Chrome debugger tool. It shows a right string, but no image is pointed.
I'm using a local computer with Windows 7 and the image is in the same directory as the html source.
So I'm crazy ...
Update:
I also have tried, with no success: (I also saw the html in Chrome DevTools )
c.appendChild(document.getElementById("header").cloneNode(true))
// where c is the image's parent element
It's amazing because the original image works, when using innerHTML
I've made more research and I've discovered a great solution without the need for a popup tab. The magic was made by iFrame. An empty one:
<iframe id="luck" style="border:none;" >
</iframe>
In other point, I've placed the content to be printed (with images)
<div class="printer" style="margin:0; padding:0; display:none">
...
</div>
Display is set with "none" (since I don't want to display that content on the page).
The print code is below in just 2 lines (long ones):
function procPrint() {
document.getElementById("luck").contentDocument.body.innerHTML =
document.getElementsByClassName('printer')[0].innerHTML;
setTimeout(function() {luck.contentWindow.print();},10);
// just 10 ms waiting time is enough,
// maybe complex content demands more.
}
Advantages:
No popup. Cancel or OK resumes the original page.
Print dialog is not missing. No tab to be changed.
Disadvantages:
Rendering of innerHTML assignment demands setTimeout use.
Firefox does not give an error, but the printing does not work. My goal is just a prototype. So for me, I'm ok.
-/-
I did not testing the src bug (correct string don't display the image) with DOM assignments.
I'm satisfied with what I got. I hope it will be useful for someone.
Update:
I've discovered that iFrame printing ignores completely CSS resources like a printing CSS file:
<link rel="stylesheet" type="text/css" href="/print.css" media="print" />
or #media print specs inside a CSS file like:
#media print {
body { font-size: 14pt }
}
It occurs because logically the frame is another document. So the style needs to be attached in the HTML that will be cloned inside iFrame or it's possible includes css file dinamically in the child after cloning HTML inside the iFrame (see here).
My brain understand the logic, but it's weird: If you puts a style in the HTML printing source it works, but if you use the class name in the CSS file, it changes the clone source but not in the cloned nodes.
If one needs to change or set the background color (or image) in the printing, changes directly in the body iframe. One specifies background color in the cointaner doesn't make the work.
In this case, add the below line in procPrint function above.
d.style.backgroundColor = "#FF0000";
Update 2
For invisible iFrame on the screen uses:
#media screen{
.printonly, .printonly * {
display: none !important;
}
}
Related
I have two Javascript files, both setup to generate an image from base64. The first script, called static.js looks like this.
var element = new Image();
element.src = "data:image/png;base64,..."
document.body.appendChild(element);
I can embed the script into my website using the following code and the image appears with no issues. (To see the full code, including the base64, go here)
<body>
<script src="./static.js"></script>
</body>
Similarly, I have a second script that I found on CodePen by takashi that converts a base64 image into an animated glitch. I was able to take that code and modify it using the same base64 image as the static code but with the glitch (apologies, but the code is really long even without my base64 image so I just included the link). The code for my image can be seen here. Note that while CodePen shows the HTML and Javascript on the same page, I broke mine out into separate files.
Again, if I embed the script into the webpage, it works with no issues.
<body>
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/0.5.7/p5.min.js"></script>
<script src="./glitch.js"></script>
</body>
The issue I have is that neither code has a dedicated javascript function() attribute, so the only way they work is if I embed the code as indicated above. Using the static image for brevity, if I add a dedicated function:
function isStatic() {
var element = new Image();
element.src = "data:image/png;base64,..."
document.body.appendChild(element);
}
and then try a callback,
<body>
<script src="./static.js">
isStatic();
</script>
</body>
the image does not appear on the webpage any longer. The same happens on the glitched image when I try to wrap the whole script into a function and then try a callback.
The main reason I was trying to turn each JS file into functions is so that I could combine the two into one file (which I did), and then using an embedded script like
<script>
setInterval(function(isStatic) {
// This will be executed every 9 seconds
}, 9000);
setInterval(function(isGlitch) {
// This will be executed every 2 seconds
}, 2000);
</script>
to create an image that switches from static to glitched, and then back again.
Since I was not able to successfully turn each JS file/script into it's own function, what I am trying to figure out is if there is a better way to combine my Static and Glitch JS scripts into one, or if there is a way that I can set the webpage to call each script file individually in such a way that creates a loop of the static and glitched images switching back and forth.
I have scoured the Google-webs looking for anything that describes what I am trying to do visually, but have absolutely nothing to show for it but a whole heap of scripts on various ways to make text and/or images glitch (just not how to make them start out static and then glitch randomly). Essentially what I would like to do with my two scripts is
- run static image (script or call) for *x* seconds (120-180 seconds)
- run glitched image (script or call) for *x* seconds (3-5 seconds)
- reset (loop) the sequence
in order to create the appearance of a single image that seems to randomly glitch for unknown reasons.
Edited answer after your clarifying comment:
Your code uses a library called p5, which is controlling your animation timing, so my previous answer is irrelevant. If you just want to change how often the glitch occurs, you already have almost everything you need. The glitch.js file already has a flag to turn the glitch on and off (this.throughFlag). And, it already has a slight random delay between glitches on line 226:
setTimeout(() => {
this.throughFlag = true;
}, floor(random(40, 400)));
The second parameter to setTimeout controls how long to wait beofre setting this.throughFlag to true (and thus starting to glitch again).
You just need to make this number longer. To do so, you want to make the time on the timeout longer, ie by multiplying it by some constant, which I'll call delayFactor.
const delayFactor = 10;
setTimeout(() => {
this.throughFlag = true;
}, delayFactor * floor(random(40, 400)));
See it in action here.
I am working on a web widget that can be embedded on 3rd party websites.
Since a lot of content management systems do not allow users to post/execute scripts, I want my widget to show an image instead of JS-generated content if such situation occurs.
<script type="text/javascript">
(function(){var s = document.createElement('script');s.src = '//example.com/file.js';s.async = "async";document.body.appendChild(s);}());
</script>
<img src="//example.com/image.svg?param1=value1" src="" id="my_fallback">
For now I am using the code above. Is there any way to show the image only if the script did not load? The goal is to reduce transfer usage and provide better user experience.
The first line of my widget script is removing #my_fallback, but it is not fast enough - sometimes I can see the image for a second before the actual widget content replaces it.
The only thing I came up with is to delay creation of the image by including something like sleep() in the beginning of my image generator.
EDIT
No, <noscript> won't work here. I do not want to fallback if user has disabled javascript. I want to fallback when a script has not loaded - for any reason, especially if some security mechanism cut off the <script> section.
Use html tag Noscript
<noscript>Your browser does not support JavaScript! or a image here</noscript>
Remember
In HTML 4.01, the tag can only be used inside the element.
In HTML5, the tag can be used both inside and .
Edit : -
add one html tag
<span class="noscript">script is loading.....or put image</span>
inside your script tag
now in your scripts which has to be load add one code like
add this line at the end
$('.noscript').hide();
This is the other way which you can handle the same!
One quick fix is to create a global variable from that script, visible to the window object.Also the image must be hidden. Then, on a main.js script check for that variable. If it exists then run your widget code from there. If it doesnt exist then fadeIn the fallback image.
Heres a demo
The default img is an image 272x178 size and the widget image is an image 300x400 size.
To simulate the action when the script is unavailable, just name the variable myWidgetIsEnabled with a different name so the condition fails.
Here is some code:
// Code goes here
var widget = (function(){
window.myWidgetIsEnabled = true;
return {
init: function(){
var s = document.createElement('script');s.src = 'file.js';s.async = "async";
document.body.appendChild(s);}
}
}());
$(document).ready(function(){
if(window.myWidgetIsEnabled){
widget.init();
}else{
console.log('not enabled, the default behavior');
$('.fallback').fadeIn();
}
})
I'm a creating a loading screen for website I am making. The website loads many images, scripts, etc. The HTML and CSS part is great, but I need a way to guarantee that the "loading..." image will be loaded before anything else.
I'm using jQuery, and everything is initiated within $(function () { ... });. I imagine that the code for this would need to be called before/outside that block, and the code to remove the loading screen will be called at the very end of that block. Currently, the loading image is set as a DIV background, which is the way I prefer it. However, if it's completely necessary, I will settle for an IMG tag.
Update: (solution)
I was able to answer my own question by using a combination of Robin and Vlad's responses. Both were very good, and excellent answers, however the problem is that they were aimed to load an image before another image, rather than load an image before anything else. (CSS, JS, etc...)
Here's the dirty version of what I came up with:
var files = [new Image(), document.createElement('link'), document.createElement('script')];
files[0].setAttribute('src', 'images/loading.gif');
files[1].setAttribute('rel', 'stylesheet');
files[1].setAttribute('type', 'text/css');
files[1].setAttribute('href', 'test.css');
files[2].setAttribute('type', 'text/javascript');
files[2].setAttribute('src', 'js/jquery-1.5.1.min.js');
window.onload = function (e) {
document.getElementsByTagName('head')[0].appendChild(files[1]);
document.getElementsByTagName('head')[0].appendChild(files[2]);
}
Taking a look at the load sequence on the network tab of Chrome's developer console shows that 'loading.gif' is loaded first, then 4 dummy images, then 'test.css', and then 'jquery.1.5.1.min.js'. The CSS and JS files don't begin to load, until they've been inserted into the head tag. This is exactly what I want.
I'm predicting that I may begin to have some problems, however, when I begin to load a list of files. Chrome reports that sometimes the JS file is loaded first, but the majority of the time the CSS file is loaded first. This isn't a problem, except when I begin to add files to load, I will need to ensure that jQuery is loaded before a script file that uses jQuery.
If anyone has a solution for this, or a way to detect when the CSS/JS files are finished loading, using this method, then please comment. Though, I'm not sure that it's going to be a problem yet. I may need to ask a new question in the future about this, if I start to run into problems.
Thank you to every who has helped with this issue.
Update: (glitch fix)
I ended up running into a lot of problem with this method, because the script files were being loaded asynchronously. If I would clear the browser cache, and then load the page, it would finish loading my jquery dependent files first. Then if I refreshed the page, it would work, because jquery was loaded from cache. I solved this by setting up an array of files to load, then putting the load script into a function. Then I would step through each array item using this code:
element.onload = function() {
++i; _step();
}
element.onreadystatechange = function() {
if (("loaded" === element.readyState || "complete" === element.readyState)) { ++i; _step(); }
}
You can reuse resource prealoding browser support.
I'm not sure it works across all browsers but in my case this approach helps me to load images first. Also it allows to define concrete images so UI specific could be skipped
First define in header what resource you want to preload and define resource priority
<link rel="preload" href="link-to-image" as="image">
or
<link rel="preload" href="link-to-image">
Second line allow to increase loading priority across all object types (scripts / images / styles). First line - only through images.
Then define in body link to image as usual:
<img src="link-to-image" alt="">
Here is my working example
https://jsfiddle.net/vadimb/05scfL58/
As long as the "loading..." image is positioned before any other html elements, it should load first. This of course depends on the size of the image. You could put the loading div right after the tag and position it using 'position:absolute'.
Regarding the code to remove the loading screen, one method is to do the following.
Put all the images, scripts that need to be loaded in a hidden div (display: none)
Set up a variable that will hold the total of the images / scripts to be loaded
Set up a counter variable
Attach to each image / script the "onload" event
Everytime the "onload" event is triggered it will call a function that will increment the counter variable and check if the value of the counter equals the value of the total variable
If all resources have been loaded, fire a custom event that will show the div with the images, and hide the div with the loading screen.
The code below isn't tested so it might not work. Hope it helps
var totalImages = 0;
var loadCounter = 0;
function incrementLoadCounter() {
loadCounter++;
if(loadCounter === totalImages) {
$(document).trigger('everythingLoaded');
}
}
function hideLoadingScreen() {
$('#loadingScreen').hide();
$('#divWithImages').show();
}
$(document).ready(function(e) {
$('#loadingScreen').bind('everythingLoaded', function(e) {
hideLoadingScreen();
});
var imagesToLoad = $('img.toLoad');
totalImages = imagesToLoad.length;
$.each(imagesToLoad, function(i, item) {
$(item).load(function(e) {
incrementLoadCounter();
})
});
})
I'm not sure if it's possible to enforce.
If it is, try adding this in the head-tag:
<script type="text/javascript">
if(document.images)
(new Image()).src="http://www.image.com/example.png";
</script>
In theory that may load and cache that image before anything else.
I think if you place the IMG tag at the top of your html body it will be loaded first. If you do not want to move your div just use a copy of the image tag. Once the images is loaded it will be shown in every image tag which shows the same picture.
Or you could use spin.js as loading image. It display this "loading cycle image" via javascript.
Check it out under:
http://fgnass.github.com/spin.js/
I used JavaScript to modify some style on the page and then alert the modified style. In IE v7, though the alerted message shows that the change has been made, visual rendering of the page shows no difference. The same code however works fine in FF. What could the reason be? Another thing i noted is when i used a developer toolbar's script console I was able to get the expected results but not when i put the js in a script tag.
Sample Code -
function change()
{
var text=document.getElementsByTagName("h2");
var i=0;
var p=text[0];
while(p)
{
alert(p.style.cssText);
p.style.cssText="color:#565656;";
p.innerHTML="Changed";
alert(p.parentNode.innerHTML);
i++;
p=text[i];
}
}
This was simply put in a script tag and put inside body just to test. The change made to innerHTML or style is not reflected in IE browser window though the later JavaScript alert shows the change.
Instead of changing the style that way, directly set the "color" property:
p.style.color = '#565656';
I'm loading image tags via AJAX and inserting them with the conventional .html(content) function in jQuery alongside a bunch of other HTML. However, this question still applies if you're loading a page from scratch. Now, I have a background image placeholder to be put there while the image loads. I want this background image to go away when the image loads.
Problem:
If I attach a conventional .load(function) event listener, I am concerned that the image might load before the hook is applied (putting the hook in a small JS <script> right after the image instead of in a $(function(){}) block might help a bit). I have yet to encounter such behaviour, but I know of nothing in the specification that prevents this from happening (since the image tag ought to be fully parsed before the hook is applied).
My current solution. Put the command in an inline onload= property within the image tag.
Is there a better way?
Up until a week or so ago I would have been lost too. Thankfully this answer to another question will help you out:
Basically put this in $():
$(function(){
var img = $("#idofimage").load(function () {
/* your magic to swap out placeholder */
});
if (img[0].complete) {
// Trigger the load handler if the image
// is already loaded
img.trigger('load');
}
});
You don't need jQuery for this, you can do it with CSS.
.my-img-loader-class { background:url('placeholder-or-progress'); }
Or if you don't want to change your HTML:
#container img { background:url('placeholder-or-progress'); }
To show placeholders while images are loading in a specific div.
The way it works is the image element will show the placeholder image as its background, and when the src loads it will appear above the placeholder, so as to replace it nicely.