Creating new html in JS or ajax loading a html layout? - javascript

I have a page where I need to create a large amount of HTML that's not already present in the page.
Using jQuery I've been building the page with JS piece by piece, adding divs here and there, etc, until I get my layout.
Right now I'm thinking rather than do all that in JS, I can create the layout in a separate HTML file and then load it with ajax. My initial aversion to that idea is because of ajax, it requires an additional server request, and might end up slow(er?).
Anyone have any advice on whether or not this is a good idea, and if it is, if there are tutorials, set ways and patterns to doing this sort of thing.
Thanks.

There may be a speed impact from making another round-trip to the server. However, I think that the readability/maintainability you gain from having all of your HTML in a separate template, rather than mixed in with your JS is the big win here. You won't have to deal with quote issues, entity encoding, all of that. And the code that you do have will be easier to debug.
I'm not aware of any specific tutorials on this, but with most of the AJAX libraries out there, it's easy to make an XHR request and pipe the response into a DIV. For example, see Prototype's Ajax.Updater(container, url[, options]) function. ( http://www.prototypejs.org/api/ajax/updater )

The issue you'll get is not slower, but your URLs will be a little messed up.
If you navigate from page to page your URL won't update easily. You CAN do it but it can be a lot of work.
I've used post's callback function to display the data from the post with good effect and it's fast.
Good luck with it!
edit: I was talking about jQuery's post function.
2nd edit: If you're going to vote me down guys, at least say why...

Related

Get data from another HTML page

I am making an on-line shop for selling magazines, and I need to show the image of the magazine. For that, I would like to show the same image that is shown in the website of the company that distributes the magazines.
For that, it would be easy with an absolute path, like this:
<img src="http://www.remotewebsite.com/image.jpg" />
But, it is not possible in my case, because the name of the image changes everytime there is a new magazine.
In Javascript, it is possible to get the path of an image with this code:
var strImage = document.getElementById('Image').src;
But, is it possible to use something similar to get the path of an image if it is in another HTML page?
Assuming that you know how to find the correct image in the magazine website's DOM (otherwise, forget it):
the magazine website must explicitly allow clients showing your website to fetch their content by enabling CORS
you fetch their HTML -> gets you a stream of text
parse it with DOMParser -> gets you a Document
using your knowledge or their layout (or good heuristics, if you're feeling lucky), use regular DOM navigation to find the image and get its src attribute
I'm not going to detail any of those steps (there are already lots of SO answers around), especially since you haven't described a specific issue you may have with the technical part.
You can, but it is inefficient. You would have to do a request to load all the HTML of that other page and then in that HTML find the image you are looking for.
It can be achieved (using XMLHttpRequest or fetch), but I would maybe try to find a more efficient way.
What you are asking for is technically possible, and other answers have already gone into the details about how you could accomplish this.
What I'd like to go over in this answer is how you probably should architect this given the requirements that you described. Keep in mind that what I am describing is one way to do this, there are certainly other correct methods as well.
Create a database on the server where your app will live. A simple MySQL DB will work, but you could use anything. Create a table called magazine, with a column url. Your code would pull the url from this DB. Whenever the magazine URL changes, just update the DB and the code itself won't need to be changed.
Your front-end code needs some sort of way to access the DB. One possible solution is a REST API. This code would query the DB for the latest values (in your case magazine URLs), and make them accessible to your web page. This could be done in a myriad of different languages/frameworks, here's a good tutorial on doing something like this in Node.js and express (which is what I'd personally use).
Finally, your front-end code needs to call your REST API to get the updated URLs. This needs to be done with some kind of JavaScript based language. jQuery would make this really easy, something like this:
$(document).ready(function() {
$.Get("http://uri_to_your_rest_api", function(data) {
$("#myImage").attr("scr", data.url);
}
});
Assuming you had HTML like this:
<img id="myImage" src="">
And there you go - You have a webpage that pulls the image sources dynamically from your database.
Now if you're just dipping your toes into web development, this may seem a bit overwhelming. But I promise you, in the long run it'll be easier then trying to parse code from an HTML page :)

Duplicate an HTML file (and its content) with a different name in Javascript

I have an HTML file with some Javascript and css applied on.
I would like to duplicate that file, make like file1.html, file2.html, file3.html,...
All of that using Javascript, Jquery or something like that !
The idea is to create a different page (from that kind of template) that will be printed afterwards with different data in it (from a XML file).
I hope it is possible !
Feel free to ask more precision if you want !
Thank you all by advance
Note: I do not want to copy the content only but the entire file.
Edit: I Know I should use server-side language, I just don't have the option ):
There are a couple ways you could go about implementing something similar to what you are describing. Which implementation you should use would depend on exactly what your goals are.
First of all, I would recommend some sort of template system such as VueJS, AngularJS or React. However, given that you say you don't have the option of using a server side language, I suspect you won't have the option to implement one of these systems.
My next suggestion, would be to build your own 'templating system'. A simple implementation that may suit your needs could be something mirroring the following:
In your primary file (root file) which you want to route or copy the other files through to, you could use JS to include the correct HTML files. For example, you could have JS conditionally load a file depending on certain circumstances by putting something like the following after a conditional statement:
Note that while doing this could optimize your server's data usage (as it would only serve required files and not everything all the time), it would also probably increase loading times. Your site would need to wait for the additional HTTP request to come through and for whatever requested content to load & render on the client. While this sounds very slow it has the potential of not being that bad if you don't have too many discrete requests, and none of your code is unusually large or computationally expensive.
If using vanilla JS, the following snippet will illustrate the above:
In a script that comes loaded with your routing file:
function read(text) {
var xhr=new XMLHttpRequest;
xhr.open('GET',text);
xhr.onload=show;
xhr.send();
}
function show() {
var text = this.response;
document.body.innerHTML = text;//you can replace document.body with whatever element you want to wrap your imported HTML
}
read(path/to/file/on/server);
Note a couple of things about the above code. If you are testing on your computer (ie opening your html file on a browser, with a path like file://__) without a local server, you will get some sort of cross origin request error when trying to make an XML request. To bypass this error, either test your code on an actual server (not ideal constantly pushing code, I know) or, preferably, set up a local testing server. If this is something you would want to explore, its not that difficult to do, let me know and I'd be happy to walk you through the process.
Alternately, you could implement the above loading system with jQuery and the .load() function. http://api.jquery.com/load/
If none of the above solutions work for you, let me know more specifically what it is that you need, and I'll be happy to give a more useful/ relevant answer!

A good way to pass information javascript?

I have an asp.net website, but I need to pass stuff to javascript to do stuff there. At the moment, I am doing things like this:
<script type="text/javascript">
var userHasMicrositePhoto = '<%=hasMicrositePhoto%>';
</script>
But I've been told that putting lots of script tags in like this is bad, and also its annoying to have to keep writing Properties in my code behind.
What is a better way to do this?
This is pretty much the ideal way to go IMO. If you have a lot of stuff like this, try putting it all in one <script>block. You could also use an array to reduce the code overhead, or have asp.net output a JSON encoded array with all the needed properties in it.
Depending on your architecture, you could consider fetching those properties through a separate Ajax request which would make the page body a bit cleaner, but it would be an extra request that can't be cached, so I would use this only in very extreme cases.
The same applies to embedding a separate <script src=....> it looks nicer in the generated markup, but needs another request to the server.
The only alternatives would be
write a page that generates AJAX and have your JavaScript access
that with XHR
write a page that generates JavaScript and have your
HTML access that with a single script tag
I don't think either of those solutions are obviously superior to what you're doing now, except they could be used by other pages more easily, if that helps.
I would use JSON when you're passing information to be used by javascript.
This may require you to reconsider how you're developing your website or application. I usually use it when the server is passing information via ajax but ajax isn't the only solution.
http://code.google.com/p/aspjson/
http://www.json.org/
I may not quite understand your question though so forgive me if I am totally off.

Run a JavaScript function from a URL

I need to link to a page that uses javascript to create the appearance of different pages. Each of the links on the page I am pointing to calls a javascript function that produces the "new" page. So, if I just link to the page, I get the default configuration. But what I need to link to is a particular configuration after the js function has run.
At first I thought I would be able to append the function to the url, but apparently that functionality is not supported for security reasons (is this correct?). Is it possible to post the values?
Does anyone know how I can display the correct configuration?
In the general case, no, it's not possible, which is why these sort of JavaScript-only pages are an inaccessible, unusable total pain in the neck and people should stop creating them, the idiots.
If you are lucky and the site you're talking about has actually Done It Properly, then they'll have used #fragment navigation, so when you click a link it does a history-able and bookmark-able navigation, updating the URL to one with a #something at the end that you can use to navigate back there. If you're really lucky, there might even be a fallback URL for non-JavaScript browsers that you could link to. But more often all there is is a JS function, which you can't link to or invoke outside of that site, leaving you quite out of luck should you want to deep-link anything.
(Did we learn nothing from the <frame> fiasco, guys? All you trendy webmasters hacking up clever-clever swooshy jQuery-animated load()-powered multiple-pages-in-one sites are churning out rubbish that is no better than the frame-addled worst of the Netscape 3 era. Stop it. Seriously.)
Okay, I was given the solution by a friend. It seems I should answer my own question. In fact, I felt a little silly once I saw how simple the solutions was. I just forgot how to plant "posts" in a URL. It seems the question itself was erroneous.
All I really needed to do was set some Javascript variables in a page I don't own. Solution looks something like this.
http://www.apage.com/control.aspx?var1=someVal&var2=someVal...&varn=someVal
Thanks to those who responded.
The owner of the page could do you a favour and provide a mechanism to run functions depending on a value in the querystring.
Otherwise there may be something that can be done with ajax but it could be messy.

What are benefits of serving static HTML and generating content with AJAX/JSON?

https://urbantastic-blog.tumblr.com/post/81336210/tech-tuesday-the-fiddly-bits/amp
Heath from Urbantastic writes about his HTML generation system:
All the HTML in Urbantastic is completely static. All dynamic data is sent via AJAX in JSON format and then combined with the HTML using Javascript. Put another way, the server software for Urbantastic produces and consumes JSON exclusively. HTML, CSS, Javascript, and images are all sent via a different service (a vanilla Nginx server).
I think this is an interesting model as it separates presentation from data physically. I am not an expert in architecture but it seems like there would be a jump in efficiency and stability.
However, the following concerns me:
[subjective] Clojure is extremely powerful; Javascript is not. Writing all the content generation on a language created for another goals will create some pain (imagine writing Javascript-type code in CSS). Unless he has a macro-system for generating Javascript, Heath is probably up to constant switching between JavaScript and Clojure. He'll also have a lot of JS code; probably a lot more than Clojure. That might not be good in terms of power, rapid development, succinctness and all the things we are looking at when switching to LISP-based langauges.
[performance] I am not sure on this but rendering everything on user's machine might lag.
[accessibility] If you have JS disabled you can't use site at all.
[accessibility#2] i suspect that a lot of dynamic data filling with JavaScript will create cross-browser issues.
Can anyone comment? I'd be interested in reading your opinions on this type of architecture.
References:
Link to discussion on HN.
Link to discussion on /r/programming.
"All the HTML in Urbantastic is completely static. All dynamic data is sent via AJAX in JSON format and then combined with the HTML using Javascript."
I think that's the standard model of an RIA. The emphasis word seems to be 'All' here. Cause in many websites a lot of the dynamic content is still not obtained through Ajax, only key features are.
I don't think the rendering issues would be a major bottleneck if you don't have a huge webpage with a lot of elements.
JS accessibility is indeed a problem. But then, users who want to experience AJAX must have JS enabled. Have you done a survey on how many of YOUR users don't have it enabled?
The advantage is, you can serve 99% (by weight) of the content through CDN (like Akamai) or even put it on external storage (eg. S3). Serving only the JSON it's almost impossible for a site to get slashdoted.
When AJAX began to hit it big, late 2005 I wrote a client-side template engine and basically turned my blogger template into a fully fledged AJAX experience.
The thing is, that template stuff, it was really easy to implement and it eliminated a lot of the grunt work.
Here's how it's was done.
<div id="blogger-post-template">
<h1><span id="blogger-post-header"/></h1>
<p><span id="blogger-post-body"/><p>
<div>
And then in JavaScript:
var response = // <- AJAX response
var container = document.getElementById("blogger-post-template");
if (!template) { // template context
template = container.cloneNode(true); // deep clone
}
// clear container
while(container.firstChild)
container.removeChild(template.firstChild);
container.appendChild(instantiate(template, response));
The instantiate function makes a deep clone of the template then searches the clone for identifiers to replace with data found in the response. The end result is a populated DOM tree which was originally defined in HTML. If I had more than one result I just looped through the above code.

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