newbie question.
I've read some of the W3Schools, I also read a lot from other sources on the internet, however I can't find what I need, and I'm sure it's quite simple to you.
I'm using ASP.Net, and I want to add to my website, multiple items, which every item hold a picture, and some other information, including links. I'm pretty sure I don't need to write the code for every item in the HTML source, and I don't know exactly how to implement my this.
The basic idea is that my items will be imported from a Database that I create in visual studio, and I want to style my webpage so they would appear in a certain formation, I thought I might need to use Javascript or CSS for this, hope I'm not mistaken.
Javascript isn't some sort of magician that will render all your stuff on its own. However, you can use it to attach a template to every of your items.
What you have to do is :
Create a base HTML template for 1 of your item that can be applied to all of them
Create a Javascript function that will attach thoses CSS classes and HTML attributes to every element out of your DB (or you could use a templating frameork .. since there's a lot of them I'll let you look for it on Google. It's pretty easy to use)
On page load or whatever event you want to bind on, you call your function which will attach the CSS and HTML to every element out of your DB and will render it on your page
Enjoy what you've done.
I hope this helps. Good luck ! ;)
Related
I've been looking everywhere and I can't seem to find exactly what I'm looking for, I'm starting to think I should be looking at some kind of Javascript?
Basically, I have an amount £1,000,000 displayed over an image button and I need this repeated on a different page (The page the button leads to).
As I've never done this before I'm not sure where to look or what I need to be looking at as I'm a novice in this area.
Any help would be appreciated.
If the value is static so you can use content css property :
https://developer.mozilla.org/fr/docs/Web/CSS/content
If the amount is dynamic you should pass variable through Url or via form.
As I don't have a clue as to what you're setup is, i'll make some assumptions:
a static HTML site
no javascript frameworks (so no jQuery or jqLite etc)
with these assumptions you should start by looking up url attributes as a way to communicate basic information between pages.
As an example, the button href should look something like this:
/link-to-page?amount=1000000
then you grab the amount on the new page - with javascript - looking in the window.location object
This is a good resource
I noticed on youtube that replies to each comment are inside a <div id="replies">. So the same id is used for every comment reply group.
When is it a good practice to give same ids to multiple similar elements?
I know ids should be unique, that's why I'm wondering about this.
To check it, go to a youtube video, inspect and select the reply area of a comment. Optionally, Ctrl+F in inspect and search replies.
YouTube uses web components which might be the reason there are multiple of the same IDs. Web components are encapsulated chunks of HTML, javascript, and CSS that you can drop into your pages. You can read more about them here: https://www.polymer-project.org/
So my thinking of why YouTube specifically has multiple of the same ID is that the replies component itself has an ID of replies and is being targeted on a component level rather than a global.
I hope this makes sense? Even if it doesn't, try to avoid ID's that aren't unique like the others mentioned.
One of the reason YouTube can have duplicate IDs, completely invalid looking html and still get away with it, it's because they are generating dynamic content. Remember, even though it is incorrect, the browser will render it just fine. They are not using the ID to mark a unique element, but more as metadata.
Note that Youtube uses custom html tags that I assume helps them reuse code for not just the website, but also for their app.
Read more about custom elements
Update: Just wanted to show an example on how generating content through an application can help you get away with things that could otherwise be a problem.
Writing Inline css is not recommended mainly because it becomes impossible to maintain the larger the css becomes. However, you can code it in an external file during development, then compile it to be inline using an application and have none of the headaches.
See example
As a new web developer, I've been utilizing a lot of resources like StackOverflow to assist me in the learning and development process.
When using jQuery, all of the examples/responses that I've come across so far have only referenced classes, like so:
$('.yourClass')
as opposed to
$('#yourID')
Seeing that class referencing seems to be the trend (I honestly haven't found one author who writes a jQuery to an ID), are there any pitfalls I should be aware of for using ID's w/ jQuery or JS in general? Thanks!
EDIT 1: I'm aware that ID's are for single-items, classes are for accessing multiple items. I'm more interested in why I don't see any jQuery or JS examples referencing ID's. Thank you!
You would have to ask each author on a case-by-case basis, but generally when creating examples, the selector used doesn't matter; what's important is that you have a jQuery collection that you can call a method on.
By using a class selector in the example, you avoid newbie developers claiming that your plugin doesn't work when they try to use it on multiple elements with the same ID. Your example serves the purpose of showing how to use it on one or more elements, rather than just one.
People like to use classes because ids have to be unique across the whole page. When trying to make reusable, pluggable components, id's make this impossible to enforce.
Exception: the new web-components standard allows you to encapsulate ids to just your component.
An ID must be unique, you can have only one (like highlanders).
Classes are used to identify a "type" of object not a specific one.
An obligatory car analogy:
An ID is a license plate, unique to one specific thing #345-abc
The class relates to a whole category of things like .truck
Take note that a selector like $(".something") will actually be capable of producing a list of DOM elements; as it will select all DOM elements with the class of "something"
An ID selector $("#unique") will only ever return one element
Think of your HTML and CSS first.
Using Classes
If you have multiple HTML elements which all will look, feel and behave in the same way, then it is highly recommended to use a class to represent their style and behavior.
Example: rows or columns on a table, navigation buttons which animate in the exact same way, wrapper to images which have the same size throughout your website, etc.
Using ID's
However, if you have a unique HTML element which represents a particular thing or state or action in one of your pages, then that element should contain an id.
Example: pop up modal, a unique looking button, unique sections on your website which you can navigate to by their id, etc.
Then, you can use this behavior in your JavaScript and jQuery or whatever else you like to use.
Further reading
I know that you are fully aware of why we should use ID's or classes.
But the vast majority of answers that are given here, are thinking of a project context.
So, let's say editing a .js file that is linked to the scope of the entire project, the idea here is to be as reusable as possible, so that's why you'll see much more classes references than ID's. Is hard to maintain a project js file that makes reference to different ID's that are abroad the project.
Same thing will apply to css.
I hope the answer is enough, be free to post a comment or suggestions. :-)
I am working on a simple Cordova app with about 4 page types and I am trying to think through which is the better way to handle the inner HTML templates.
Hidden HTML hard coded into the HTML files that is hidden and populated/revealed by my JS.
Using a JS template system and appending and removing from the DOM.
I feel that appending all that to the DOM for a page is inefficient when I could just update the sections that change. But perhaps an append is lightweight enough where I shouldn't worry about it.
There are a number of ways you can do it. In terms of load on the browser. That is hard to say. From your question it is hard to know what is in these pages, what are you displaying, is it live data, static html etc.
When you first plot out an app, if you are from the old class of building multiple page websites, it can be a little concerning as to how well your app/page will run with all those pages crammed in to one, and all that data plus code.
The answer is, amazingly well. If done properly in modern browsers, and for example Ipads the app will run to near native performance.
The options you have are
Map all the pages into one HTML document. Hide each page content using css display:none, flip them into view using css animation, fading or just display:block.
Use a javascript routing library to map urls to blocks of code that deal with each page, this makes mapping out your app much easier, and means that buttons can just link to your pages, like a real website. see http://projects.jga.me/routie/
Building all the page templates into one page can make it hard to code, as the page becomes enormous, consider breaking the inner content of each page into separate files, you can then give each page holder a url and use a small xhr request to load the page on-the fly, once loaded you can cache it into memory or even local-storage, depending on whether you remove it when it is closed or keep it hidden.
In my experience you can put an enormous number or nodes into one page and have very little speed drop, bear in mind if you use something like jquery and do a lot of $(".page > .page1 > .items li") your going to have a slow app.
Tips
Use element ID's everywhere document.getElementById(..) is 100's of times faster in a loop that $(...)
cache elements when you find them, if you need them later store them in a memory cache.
keep for loop inner code to a minimum.
use a decent click touch libary like http://hammerjs.github.io/ and delegate all the events of the body tag or at least on each page.
If you need to touch the server, load data, think dom first, device second server later. A good app is a responsive app, that responds to the user instantly.
I know this has been posted a while ago, but for the sake of the users I am going to add my answer.
I completely agree with MartinWebb but my answer will shed some light on the results of his options. I am currently working on a similar project. Please note that this answer pertains to cordova (previously called phonegap) specifically. My app has about 5 pages with +-20 different components (input's, div's, h1's, p's, etc.). This is what i tried and the result of each:
jQuery was my first option, mainly because it is easy to use and reduces the amount of code required to accomplish a said goal. Result: First time I tried this approach I though I would spice it up with animations and transformations. The result of this was a very unresponsive app. I removed the animation and transformation, however due to the nature of my application I required multiple dynamically added components and jQuery just wasn't up for the task.
Css display:none and visible:hidden was my next option. I used javascript's dom to display certain div's. Result: This works if your not planning on switching many div shortly after one another eg. a simple menu. It quickly became apparent that this wasn't going to work. Also this does not eliminate my need for the dom. Remember document.getElementById('menu').style.display = "none"; is still part of the dom. This as a solution, for me, is poor. There is a reason that var menu= document.createElement('div'); is part of the language. Which brings me to my last option.
Building a page 90% on javascript's dom was my last option. Logically I could not see how 600 lines of code cold trump one .innerHTML or .style.display = "block"; but it did. Result: It was by far the most responsive of all the solutions.
I'm not saying that all webpages should be coded with dom appending, but as I stated previously, for a cordova app of a few pages (<6), with a few components a javascript dom appending approach would be best. It takes longer to code, but you will be rewarded with control and efficiency. I would suggest coding the backbone of your app in html and populating and controlling with javascript's dom.
Best of luck.
The first option, <div>s with display:none; would be more efficient by a small margin, but you can get the best of both worlds by compiling your JavaScript and templates together into a single file using something like browserify or require.js.
I've had this happen to me three times now and I feel it's time I learned how to avoid this scenario.
Typically, I build the HTML. Once I'm content with the structure and visual design, I start using jQuery to wire up events and other things.
Thing is, sometimes the client wants a small change or even a medium change that requires me to change the HTML, and this causes my javascript code to break because it depends on HTML selectors that no longer exist.
How can I avoid digging myself into this hole every time I create a website? Any articles I should read?
Make your selectors less brittle.
Don't use a selector by index, next sibling, immediate child, or the like
Use classes so even if you have to change the tag name and the element's position in the HTML, the selector will still work
Don't use parent() or child() without specifying a selector. Make sure you look for a parent or child with a specific class
Sometimes, depending on the amount of rework, you'll have to update the script. Keep them as decoupled as possible, but there's always some coupling, it's the interface between script and HTML. It's like being able to change an implementation without having to change the interface. Sometimes you need new behavior that needs a new interface.
I think the best way to help you is for you to show a small sample of a change in the HTML that required a change to your jQuery code. We could then show you how to minimize changes to JS as you update the HTML