setInterval not refreshing data in Jade template - javascript

I have a Node app using Express and Jade. I'm pulling json data from an API and I want that data to be refreshed on the page periodically. So, my thought was to have an empty div, then inject the contents of a different route/template into that div and use setInterval to refresh it. It loads initially, but never refreshes. Here's the relevant bits of my code:
board.jade:
extends layout
block content
div(class='bodyBlock')
h1= title
div#data
layout.jade:
!!! 5
html
head
title= title
link(rel='stylesheet', href='/stylesheets/style.css')
script(type='text/javascript')(src='//ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js')
body
block content
script(type='text/javascript').
$(document).ready(function(){
setInterval ($("#data").load("/currentdev"), 5000 );
});
The /currentdev route loads data.jade:
ul
each card in inprogresscards
li(style='margin-bottom: 5px')
b #{card.color} #{card.name} #{card.idShort}
So, like I said, /currentdev is being loaded into #data initially and displaying properly on my page. But it never refreshes. It seems setInterval is acting more like setTimeout...What am I missing? Thanks...
Oh, and here's the generated HTML:
<!DOCTYPE html>
<html>
<head>
<title>Current Development Board</title>
<link rel="stylesheet" href="/stylesheets/style.css">
<script type="text/javascript" src="//ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"></script>
</head>
<body>
<div class="bodyBlock">
<h1>Current Development Board</h1>
<div id="data"></div>
</div>
</body>
<script type="text/javascript">$(document).ready(function(){
setInterval ($("#data").load("/currentdev"), 5000 );
});</script>
</html>

I think you're missing the function wrapper, like this:
setInterval(function() { $("#data").load("/currentdev"); }, 5000);
Otherwise your load() gets called immediately and its return value is what is actually used for the function argument for setInterval.

Related

JavaScript not working as an external file

I'm new to HTML, JavaScipt and everything related to programming, and I'm trying to create a simple page.
Now, I'm stuck with the following problem: I want to change the date of my main.html file, but the main.js is not working. I've already change the <script> position to inside the <body>, after the </span> and even after the </body>, without success. If the content of the main.js is within the HTML it works fine, but as a external file it doesn't.
Here is my main.html:
<!DOCTYPE html>
<html>
<head>
<link href="main.css" rel="stylesheet" type="text/css"/>
<script type="text/javascript" src="main.js"></script>
<title>Page 1</title>
</head>
<body>
<p>WRF<br>
<span id="data">18/09/1987</span></p>
</body>
</html>
My main.js is just:
document.getElementById("data").innerHTML = "JUBA";
I've looked through the internet and through this forum, but all answers that I've found did not worked.
The files are on the same directory and the main.css works fine.
Thank you in advance.
At time you call main.js element #data was not created in DOM tree. You can fix this by putting the link to your Javascript file right before closing the body like this:
<script type="text/javascript" src="main.js"></script>
</body>
Document Object Model (DOM) is not "READY".
Try use onload event, inside main.js:
window.onload = function() {
document.getElementById("data").innerHTML = "JUBA";
};
If needs more "fast" than onload, use jquery with $(document).ready:
html:
<link href="main.css" rel="stylesheet" type="text/css"/>
<script type="text/javascript" src="https://code.jquery.com/jquery-1.11.1.min.js"></script>
<script type="text/javascript" src="main.js"></script>
main.js:
$(document).ready(function() {
$("#data").html("JUBA");
});
window.onload vs $(document).ready()
Answer by #Guffa:
The ready event occurs after the HTML document has been loaded, while the onload event occurs later, when all content (e.g. images) also has been loaded.
The onload event is a standard event in the DOM, while the ready event is specific to jQuery. The purpose of the ready event is that it should occur as early as possible after the document has loaded, so that code that adds functionality to the elements in the page doesn't have to wait for all content to load.
The element is not yet accessible when you run the script.
Either you can put the script at the end of the page or delay the execution.
You could put the JavaScript in the <body> tag after the rest of the page. When the browser loads it, the <span> will already be there to be edited.
As per your code the script will be called first then page will be loaded, therefore when the script is running there will not be any element having id data because yet page have to be loaded. There are many ways to achieve what you need.
1. Add a script tag before or after end of body like
or
<script type="text/javascript" src="main.js"></script>
</body>
Write .js file above before body i.e. in head tag and write the whole javascript code in onload method.
window.onload=function(){
document.getElementById("data").innerHTML = "JUBA";
};
window.onload=function(){
document.getElementById("data").innerHTML = "JUBA";
};
<p>WRF<br>
<span id="data">18/09/1987</span></p>

The contents of a loaded div doesn't appear from a loaded HTML

I'm developing a single-page web app. What I did is that I have a main page index.html where I have all the skeleton of the app but I have in the body a div that i use to load the contents of the page that I want to show. In the loaded page I have a div whose contents need to loaded as well. The issue is that the contents of the second div doesn't appear and I can't figure out why.
I think you would need an example to better understand.
I have two html files: index.html and browse.html.
First here is browse.html:
<div id="browse_contents">
</div>
Finally here is index.html:
<html>
<head>
//load jquery
<script>
$(document).ready(function(){
$("#browse_page").load("browse.html")
$("#browse_contents").html("<p>The contents.</p>")
});
</script>
</head>
<body>
<div id="browse_page"></div>
</body>
</html
So the problem is that "The contents." doesn't appear and I can't figure out why!
Currently, #browse_contents doesn't exist in the DOM when you are attempting to change its HTML.
.load() is asynchronous, which is why it and other jQuery AJAX methods come with a callback parameter; a function to call when the request is complete:
$(document).ready(function(){
$("#browse_page").load("browse.html", function(){
$("#browse_contents").html("<p>The contents.</p>");
});
});

Can't import javascript code with innerHTML

I've built a webpage that is basically a main-page with a div that is filled with different pages by using AJAX. This basically works by loading pages into a div by using innerHTML. One problem I ran into was when a page with javascript is loaded into that div all of the other code runs fine; just the javascript doesnt work.
Main-page(index.php):
<html>
<head>
<script type="text/java">
////bunch of functions////
////Ends up that page_request on this instance is 'graph.php'////
document.getElementById('mydiv').innerHTML=page_request.responseText
</script>
</head>
<body>
<div id="mydiv"><div>
</body>
</html>
Child-page(loaded in div(graph.php)):
<html>
<head>
<link rel="stylesheet" href="mystyle.css" type="text/css" media="screen" />
<script src="other_stuff.js"></script>
</head>
<body>
<script>
///bunch of script////
</script>
</body>
</html>
Now when loading the page itself (opening graph.php) I notice that everything works fine; it is just when I import graph.php to index.php through innerHTML into my div it does not work (no errors just nothing is shown). I have read through many other posts and guides and did not come up with any distictive solution; thinks I have seen were:
Put eval() around my code [I saw on a guide that this could lead
to malicious user attacks].
Create the scripts on the main page then just import the data using:
document.createElement() and .parentNode.insertBefore()
Create a listener and call the functions when I open graph.php
And this good example
Even though I am not 100% sure how this example could work because I have php populate information for the javascript to collect and then make my graph on graph.php; so if I put that function into index.php the php will already be loaded so I would have to refresh the page or call them to update information somehow. Just for some context I am ok at php but I am new and struggle with javascript so I do not know what solution would fit my situation or work the best. Any tips/examples would be greatly appreciated, thank you for your time.
From you code snippets it seems you're looking to embed complete pages within the main page. If that's the case, a more straightforward approach would be to use an iframe element instead.
For example:
...
<div id="main-page-container">
<iframe src="some-path/graph.php" scrolling="no" frameborder="no"></iframe>
</div>
...
See reference and usage example.
I would suggest using jQuery's .load() function for this.
Take a look here: jQuery API
Older browsers such as IE8 and below don't allow you insert a string that contains javascript and execute it, in any form.
Take for instance:
function addScriptText(js_code) {
var element = document.createElement("script");
element.innerHTML = js_code;
document.head.appendChild(element);
}
will not work in IE8 and below.
You must use eval to accomplish this:
function addScriptText(js_code) {
window.eval.call(window, js_code);
}
Otherwise you need to dynamically request an external js file such as:
var script = document.createElement("script");
script.type = "text/javascript";
script.src = "externalScript.js";
document.getElementsByTagName("head")[0].appendChild(script);
Note: The page you are loading (page2.html in this example) must be on the same domain as the page that is loading it (page1.html in this example)
Working solution with jQuery:
Page 1:
<!DOCTYPE html>
<html>
<head>
<title>Page 1</title>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script type="text/javascript">
$(function () {
$("#page2").load("page2.html");
});
</script>
</head>
<body>
<h1>Page 1 Header</h1>
<div id="page2">
</div>
</body>
</html>
Page 2:
<h2>Page 2 Header</h2>
<script type="text/javascript">
alert("Page 2 loaded and javascript executed!");
</script>

Avoid GET of all contents of the HTML DOM

Context
I have a HTML5+CSS+JS slideshow designed to be synchronized between 50 clients in a domestic LAN with one wireless router.
Problem
Since the contents of the slides (mainly pictures) may be too heavy, I want to load them dynamically for each slide (e.g. as the client clicks a "next" button), since currently the site GETs all the files for every slide from the server at the beginning when the page is loaded, overloading the router.
In this question (another approach for the same problem) an user suggested me using AJAX to get only the DOM and then loading its contents dynamically. Nevertheless, his solution doesn't work for me, as the contents are loaded before the moment I want to.
Is this AJAX based approach correct? If so, what may I be doing wrong?
My code
slideshow.html (slideshow structure)
<html>
<head>
<title>My Slideshow</title>
<script src="javascripts/slidesplayer.js"></script>
<link rel="stylesheet" href="/stylesheets/style.css">
</head>
<body>
<div id="slides-containter">
<div class="slide" id="slide_1">
<!--Contents such as images, text, video and audio sources -->
</div>
<div class="slide" id="slide_2">
<!--Contents -->
</div>
<!--A bunch of slides here-->
</div>
<script>
// Here I load the slides calling a function defined in slidesplayer.js
</script>
</body>
</html>
slideshow-placeholder.html (loaded when I enter to the slideshow URL)
<html>
<head>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script src="/path/to/ajaxSlidesScript.js"></script>
</head>
<body>
<h1>Hello slides!</h1>
</body>
</html>
ajaxSlidesScript.js
$(document).ready(function() {
$.ajax('/path/to/slideshow.html', {
async : false,
complete : function ajaxCallback(slidesDOM) {
// Pull out the individual slides from the slideshow HTML
$slides = $(slidesDOM.responseText).find('.slide');
// For each one ...
$slides.each(function prepareSlide() {
// Store a reference to the slide's contents
var $slideContent = $($(this).html()); // <--- GETs all the files for this slide which I want to avoid.
// Empty the contents and keep only the slide element itself
var $slideWrapper = $(this).empty();
// Attach to focus event handled by the slideware
$slideWrapper.appendTo('body').on('focus', function injectContent() {
// Put the content in — NOW external resources should be downloaded via GET and loaded, not before.
$slideWrapper.append($slideContent);
});
});
}
});
});
Update: This approach won't work, as manipulating DOM object will cause the download of the resources even if you don't insert them in the DOM. You can see what I did in this question.
Ajax is definitive the right technology for your problem but as far as I can see your problem is simple.
<script src="javascripts/slidesplayer.js"></script>
<link rel="stylesheet" href="/stylesheets/style.css">
With this piece of code it doesn't matter if you use ajax or not because you load the CSS file already and all images referenced in this CSS file are load directly at the beginning. In addition you should load all files asynchronous.
You can add <img> tags via JavaScript and load the images asynchronous...

JavaScript code place in the header

I am not clear why its not working the javascript code when I add it to the header section as follows.
We can place a javascript code within the body as follows
<html>
<head>
<title> Simple Test </title>
</head>
<body>
<div id="mydiv"> This is the div content </div>
<script type="text/javascript" >
document.getElementById("mydiv").innerHTML=Date();
</script>
</body>
</html>
But when I place the same JavaScript code in the header section it doesn't work.
<html>
<head>
<title> Simple Test </title>
<script type="text/javascript" >
document.getElementById("mydiv").innerHTML=Date();
</script>
</head>
Can Someone please explain the issue. I know I can Write a JavaScript function in header and call it in an event. But can't we Use in this way. If Can't why.
<html>
<head>
<title> Simple Test </title>
<script type="text/javascript" >
window.onload= function (){document.getElementById("mydiv").innerHTML=Date();}
</script>
</head>
I think above code will help you to solve your problem. You can try this one.
because when the page is loaded, by the time the browser gets to that <script> element, the #mydiv element has not yet been created.
either use an "onload" event, or put your scripts at the bottom of the page.
It's because the page is being rendered in the order it's read. Therefore when the script in the header is evaluated the rest of the page hasn't been rendered yet (ie the myDiv element hasn't been created).
When you create an event handler in the head that works fine - the handler is set up before the rest of the page is loaded but the event can't happen until the element exists.
When you put it in the <head>, it runs before the <body> exists.
this is because of the page rendering order.you can access elements before it has been created. if you can, try to put all JavaScript code end of the page(before closing body tag). it will save your page load time. if you cannot put it in the bottom, put the code inside onload event.

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