I wonder why techie giants like Facebook shows many errors when validated in W3C (Link)
Is W3C required?
W3C validation is a good idea, but it is not "required". What could "required" possibly mean? I could call my ISP, get a static IP, set up a server, buy a domain, and configure HTTP to return anything I want and call it HTML if I like.
If you're doing web development and have no reason not to get it to pass W3C validation, then you should. Presumably, Facebook had a reason to ignore it - either they wanted to do something that wouldn't pass, or they didn't want to pay their engineers to make it pass, or the engineers who were responsible for it were incompetent, etc.
It's a good idea to get it to validate to ensure that you're conforming to applicable standards so that your site works well in as many standards-compliant browsers as possible.
You think the W3C validation is bad? Tell your browser to always alert you to Javascript errors, enable Javascript debugging, and go to your favorite sites.
Related
I know this is an open ended question, but hopefully it will get some good answers before the thread is locked...
I'm wondering what methods there are to programmatically check (language agnostic) if a website is online from a client perspective (assume you can't make changes to the site/server, but you can rely on certain behaviours of the site.)
The result of each method could stack to provide a measure of certainty that the site is up/down - that is, a method does not have to provide a definite indication if the site is up/down on its own.
Some common tests just to check 'upness' may be:
Ping the site (which in the case of shared hosting isn't very
indicative)
Send a http head/get request and check the status
Others I can think of to check that the site is up and functioning:
Check you received a well formed html response i.e. html to html
tags, if the site is experiencing trouble it may spit an error and
exit without writing the rest of the page (not all that reliable
though because the site may handle most errors in a better way)
Check certain content is or is not on the page, i.e. perhaps there is some content that is always present on your pages, or always present in the case of an error
Can anybody think of any other methods that could be used to help determine if a site is in fact up/down and functioning/not functioning correctly from within a program?
If your get request on a page that displays info from database comes back with status 200 and matching keywords are found, you can be pretty certain that your site is up and running.
And you don't really need to write your own script to do that. There are free services such as GotSiteMonitor, Pingdom, UptimeRobot etc. allows you to monitor your site.
Based your set of test on the unit tests priciple. It is normally used in programming to test classes, modules or other artefacts after changes have been made. You can use any of the available frameworks, so don't have to reinvent the wheel. You must describe (implement) tests to be run, in your case a typical test should request a url inside the page and then do some evaluations like:
call result (for example return code of curl execution)
http return code
http headers
response mime type
response size
response content (test against a regular expression)
This way you can add, remove and modify single tests without having to care about the framework, once you are up. You can also chain tests, so perform a login in one test and virtually click a button in subsequent test.
There are also tools to handle such test runs automatically including visualization of results, statistics and the like.
OK, it sounds like you want to test and monitor your website from a customer experience perspective rather than purely establishing if a server is up (using ping for example). An effective way to replicate the customer experience is to simulate tests against the site using one of the headless browser testing tools (phantomJS is great a great choice) as they will render the page fully (including images, CSS, JS etc.) giving you a real page load time. These tools also allow you to make assertions on all aspects of the HTML content and HTTP response.
pingdom recently started offering a (paid for) service to perform these exact types of checks for alongside their existing monitoring solution. The demo is worth looking at, their interface for writing the actual tests is very nice.
So I am attached to this rather annoying project where a clients client is all nit picky about the little things and he's giving my guy hell who is gladly returning the favor by following the good old rule of shoving shi* down the chain of command.
Now my question. The application consists basically of 3 different mini projects. The backend interface for the administrator, backend interface for the client and the frontend for everyone.
I was specifically asked to apply MOD_REWRITE rules to make things SEO friendly. That was the ultimate aim, so this was basically an exercise in making things more search friendly rather than making the links aesthetically better looking.
So I worked on the frontend, which is basically the landing page for everyone. It looks beautiful, the links are at worst followed by one backslash.
My clients issue. He wants to know why the backend interfaces for the admin and user are still displaying those gigantic ugly links. And these are very very ugly links, I am talking three to four backslashes followed by various get sequences and what not, so you can probably understand the complexities behind MOD_REWRITING something such as this.
In the spur of the moment I said that I left it the way it was to make sure the backend interface wouldn't be sniffed up by any crawlers.
But I am not sure if that's necessarily true. Where do crawlers stop? When do they give up on trying to parse links? I know I can use a .robot file to specify rules. But, as indigenous creatures, what are their instincts?
I know this is more of a rant than anything and I am running a very high risk of having my first question rejected :| But hey, it feels good to have this off my chest.
Cheers!
Where do crawlers stop? When do they give up on trying to parse links?
Robots.txt does not work for all bots.
You can use basic authentication or limited access by IP to hide back-end, if no files are needed for front-end.
If not practicable, try to send 404 or 401 headers for back-end files. But this is just an idea, no guarantee.
But, as indigenous creatures, what are their instincts?
Hyperlinks, toolbars and browser-sided, pre-activated functions for malware-, spam- and fraud-warnings...
Im attempting one of my first web applications in PHP.
There is a text box a user inputs text and clicks send. When send is clicked or when they are typing I want it to give the user an error message if they are entering forbidden characters.
But I cant really see a way to do it effectively in PHP.
Can anyone tell me what programming language would be best for this and maybe links if that would help.
However, I do not want anyone to give me the complete code for this, otherwise there is no challenge in it for me.
Thanks guys
You can use Javascript (with or without jQuery) to realtime validation. Or you use PHP to a server-side validation with IF conditionals.
Javascript Validation Sample:
http://www.w3schools.com/js/js_form_validation.asp
-- EDIT --
I recommend you validate first in the Javascript and later in PHP, because with FireBug users can edit the Javascript validation script.
There are two kinds of validation you need to consider: client-side and server-side.
Client-side validation is when the browser checks the input and reports errors as the user types, or when they hit "submit". You will probably want to use Javascript for this.
Server-side validation is when the server checks the input after the browser has submitted it. You can check this in PHP (or whatever server-side language you want - Java, C# or whatever). Note that you must do server-side validation even if you also do client-side, because you can't trust the user to submit valid data. It's pretty easy to submit bad data even when client-side validation is in use.
You need to use JavaScript because it is a client side language and can detect changed as the user is typing and such.
I have no idea about AJAX programming features. I just know that it is Asynchronous Javascript and XML.
Please help me in knowing about this language.
I have gone through many AJAX tutorials. But none of the programs are running. Why I don't know.
Do we save the file with .HTML extension?
Read:
AJAX Tutorial by W3Schools.
AJAX Programming by Google Code University
To start coding you can get the Ajax Control Toolkit by Microsoft. You should read Ajax Control Toolkit Tutorials to get a grasp of it.
You can use the free Microsoft Visual Web Developer 2010 Express Edition as your IDE.
Aside from the correct responses that the others gave you, judging from your question I think you first need to learn about client-side and server-side code.
Do we save the file with .HTML extension?
Yes and no. You will have an HTML frontend, that for instance contains a button. This will be interpreted from the client's (=user) browser. In fact it may be rendered differently depending on the browser/OS/etc.
Now, you attach some Javascript code to this button. This also runs on the client's browser, and creates a XMLHttpRequest object, either directly or through the use of a library (JQuery & Co.). Note that a library is not necessary to do an AJAX request. It will make your life easier if you do a lot of AJAX calls, but it is not essential.
And here's where the magic happens: the XMLHttpRequest object will call asynchronously (i.e.: without reloading the page) a server-side page. This may be a PHP, ASP, Perl etc etc file that does something on the server, for instance queries a database. This part of the operation is absolutely independent from the client. The user can close the browser before the server-side code finishes to load and the server will not know about it.
Once the server-side code has finished executing it returns to the client with some response data (e.g. a piece of XML, JSON, HTML or whatever you like). Finally the client executes (or not) some other Javascript code in response to this, for example to write on the screen, again with no reloading of the page, something based on what the server has returned.
Maybe I can help you understand AJAX by clarifying the concepts a bit.
Please help me in knowing about this language.
AJAX is not a language, it is a way of using existing techniques to improve the user experience of a web site. The language is Javascript in the browser but you can use any server side technique that you feel comfortable with (ASP.NET, Java, PHP, Ruby etc.)
Do we save the file with .HTML extension?
Well, that is not really the point. What you have to grasp here is that there is a server and a browser that interact with each other. Yes, you can use static HTML files for your pages (and save them as .html files), but you'll need a server to respond to the requests of the browser. This may be why your sample code is not working; you need to set up a server that works with your pages.
The whole idea behind AJAX is to improve the user experience by not reloading the entire page when a user interacts with it. You request the data you need and update the page by using Javascript to update the HTML. This is called an out-of-band or asynchronous request.
I just know that it is Asynchronous Javascript and XML.
That is what the acronym stands for but it doesn't quite cover what the technique is for, nor is it accurate any more. In the beginning XML was used to transfer data from the server to the client. People found that XML is not really that easy to work with in Javascript so now it's more common to use JSON. JSON is a snippet of javascript that can be evaluated in the browser. The snippet creates javascript object(s) that represent the data.
If you use a Javascript library, like others have suggested here, you won't have to worry about many of the details though.
Before you get into AJAX you should make sure that you understand:
HTML and CSS
Javascript
how to modify HTML with Javascript
how a browser requests information from a server
how to handle requests on the server
If you are not comfortable with all of these concepts, stick with 'regular' web pages and try to improve your knowledge step by step.
Once you get the basic knowledge from W3school, I suggest you use a framework. Usually developers do not use XMLHttpRequest at all. Instead, javascript frameworks like ExtJS, jQuery and other frameworks make your work simple. I suggest you learn bit of javascript as well. check out jQuery.
Just to add that AJAX is rarely used in its pure form with XMLHttpRequest. You will often use it as a part of AJAX UI libraries which make your life easier. If you are from the Java world - such an AJAX library is Richfaces.
Instead of worrying about how to do AJAX, use something that allows you to forget about it. Frameworks like NOLOH do AJAX (and Comet) for you automatically without you having to do a thing. Just concentrate on your application, and business logic and it does the rest.
Really, everything is done via AJAX if available, automatically. No work on your part. If you're don't want to spend much time researching it, check out this short video that was demonstrated at Confoo PHP Conference this past March http://www.youtube.com/phpframework#p/u/11/cdD9hSuq7aw.
For all those worried about, well, if it's all AJAX, what about search engines? No need to worry, http://dev.noloh.com/#/articles/Search-Engine-Friendly/.
So instead of having to worry about all these different technologies, or the client-server relationship, you can sit down, code and have your website/WebApp working in no time.
You can read about NOLOH is this month's cover story of php|architect magazine, http://www.phparch.com/magazine/2010/may/.
Enjoy.
Disclaimer: I'm a co-founder of NOLOH.
It is easy one. Ajax getting data from server side by client side execution. We have to do use XMLHttpRequest to get the result.
I am trying to find the optimal architecture for an ajax-heavy Django application I'm currently building. I'd like to keep a consistent way of doing forms, validation, fetching data, JSON message format but find it exceedingly hard to find a solution that can be used consistently.
Can someone point me in the right direction or share their view on best practice?
I make everything as normal views which display normally in the browser. That includes all the replies to AJAX requests (sub pages).
When I want to make bits of the site more dynamic I then use jQuery to do the AJAX, or in this case AJAH and just load the contents of one of the divs in the sub page into the requesting page.
This technique works really well - it is very easy to debug the sub pages as they are just normal pages, and jQuery makes your life very easy using these as part of an AJA[XH]ed page.
For all the answers to this, I can't believe no one's mentioned django-piston yet. It's mainly promoted for use in building REST APIs, but it can output JSON (which jQuery, among others, can consume) and works just like views in that you can do anything with a request, making it a great option for implementing AJAX interactions (or AJAJ [JSON], AJAH, etc whatever). It also supports form validation.
I can't think of any standard way to insert ajax into a Django application, but you can have a look to this tutorial.
You will also find more details on django's page about Ajax
Two weeks ago I made a write up how I implement sub-templates to use them in "normal" and "ajax" request (for Django it is the same). Maybe it is helpful for you.
+1 to Nick for pages displaying normally in the browser. That seems to be the best starting point.
The problem with the simplest AJAX approaches, such as Nick and vikingosegundo propose, is that you'll have to rely on the innerHTML property in your Javascript. This is the only way to dump the new HTML sent in the JSON. Some would consider this a Bad Thing.
Unfortunately I'm not aware of a standard way to replicate the display of forms using Javascript that matches the Django rendering. My approach (that I'm still working on) is to subclass the Django Form class so it outputs bits of Javascript along with the HTML from as_p() etc. These then replicate the form my manipulating the DOM.
From experience I know that managing an application where you generate the HTML on the server side and just "insert" it into your pages, becomes a nightmare. It is also impossible to test using the Django test framework. If you're using Selenium or a similar tool, it's ok, but you need to wait for the ajax request to go return so you need tons of sleeps in your test script, which may slow down your test suite.
If the purpose of using the Ajax technique is to create a good user interface, I would recommend going all in, like the GMail interface, and doing everything in the browser with JavaScript. I have written several apps like this using nothing but jQuery, state machines for managing UI state and JSON with ReST on the backend. Django, IMHO, is a perfect match for the backend in this case. There are even third party software for generating a ReST-interface to your models, which I've never used myself, but as far as I know they are great at the simple things, but you of course still need to do your own business logic.
With this approach, you do run into the problem of duplicating code in the JS and in your backend, such as form handling, validation, etc. I have been thinking about solving this with generating structured information about the forms and validation logic which I can use in JS. This could be compiled at deploy-time and be loaded as any other JS file.
Also, avoid XML. The browsers are slow at parsing it, it is a pain to generate and a pain to work with in the browser. Use JSON.
Im currently testing:
jQuery & backbone.js client-side
django-piston (intermediate layer)
Will write later my findings on my blog http://blog.sserrano.com