How can I programmatically interact with an existing web page in a web browser launched in a standard way? For example I navigate to a specific page and want to be able to run a Python script that fills some edits or clicks some elements.
This should be possible at least through IAccessible2 for main browsers, but I did not find any pointers. To put it in another way, how do screen readers do it? And bonus question, is there Python library for it?
EDIT: I am looking for something more than user input simulation. I would like to programmatically read the DOM at least, write if possible. So far I have looked at code in NVDA which is very low-level and complex. Is there anything easier?
How can I programmatically interact with an existing web page in a web browser launched in a standard way? For example I navigate to a specific page and want to be able to run a Python script that fills some edits or clicks some elements.
The answer is keyboard/mouse macros if you have to visually see the browser as it happens. You can google macro programs for your OS.
But you most likely are looking for a headless browser such as PhantomJS, HtmlUnit, TrifleJS, Splash, and SimpleBrowser
Check out - https://saucelabs.com/blog/headless-browser-testing-101
When you mention 'interact with an existing webpage in a web browser launched in the standard way' you are talking about the DOM (Document Object Model).
Many QA environments are running testing scripts on code that has not been rendered by the browser into a DOM (you see the DOM when you inspect a page using your browser tools). When you use a headless browser it creates the DOM and then runs all the tests as if a human were clicking without having to visually look at it happen.
see - https://css-tricks.com/dom/
To put it in another way, how do screen readers do it? And bonus question, is there Python library for it?
Screen readers are interacting with the DOM at a low level. I do not know if there is a Python library. Most likely this would be overkill though unless you are building a desktop app that interacts with browsers like a screen reader does.
edit...
I did some more digging and found this article that is a much more verbose explanation of how screen readers interact with the browser/dom.
Also, there is a python API for manipulating the DOM and this library seemed popular.
I am styling a project built on Meteor and using LESS. I use Brackets for styling because its Live Preview feature makes working with CSS a lot quicker and more pleasurable, but by Meteor's nature it doesn't seem possible to use this feature.
Every little change I make on the code has to be detected by Meteor, who will in turn refresh the project on the browser for me, and this process is now taking anything between 5 and 10 seconds, which is entirely too much.
Does anyone know if it's possible to work on "live" CSS/LESS, using Brackets, in a Meteor project, without having to wait for Meteor to notice my changes and take its sweet time to refresh the whole thing for me?
Or at the very least least if there's anything I can do to shorten the time Meteor takes to update?
I don't think it is possible unless the developers of Brackets go an extra mile and implement a specific support tailored for Meteor.
Brackets works on top of raw CSS and HTML files and uses Chrome Dev Tools API to manipulate the page.
Meteor doesn't send raw files to the client. HTML templates in Meteor get compiled to JS DSL and CSS is concatenated and sent in a manipulated form, too.
Bracket's live preview feature would work only with quick page layout prototyping and will not play well with any modern front-end tool chain that involves compiling pages and stylesheets or preprocessing.
Is there a way or tool that could let me step through the painting of CSS rules, one by one?
Similar as one would do in an IDE with program code, but with CSS. (But I wouldn't preferably want to do it by taking the browser's source code and stepping through its underlying functions - I just mean stepping throug "updates" by CSS rules, in a form similar to a Web Developer Toolbar.)
I expect this is usually more tedious than useful, but in some cases it would really help, in web development, like debugging cats and owls or finding out how a particular effect is achieved.
edit to clarify, by "stepping through" I mean sg. like: potentially stopping the browser from painting another rule, after each end every rule I choose, before the next one is applied (each before the "final paint" of the page is finished), for inspection of what happens.
edit 2 after BoltClock's comment, I replaced the word 'render' with 'paint', to be more clear. Removed original to be uncluttered.
Beside already mentioned webtools i guess this is only possible if the complete source code of the browser is available so its possible to either locally debug or remote debug the browser application itself with breakpoints set to the interesting "toplevel" functions.
It is for example no problem to download the source of the Java based open source browser Lobo which can then be debugged like any other application directly from your IDE like eclipse, intellij etc.
I however dont think the complete source of products like the MS Internet Explorer will ever be fully available to allow you to debug its deepest magic (which in case of MS Internet Explorer probably also takes a livetime...).
So coming back to a browser that has source code available you can either:
Have the browser beeing compiled/ run inside a IDE and directly debug your local code
Have the browser running as application allowing remote debugging and the according source code as source for a remote debugger (mostly as well from within your IDE).
This way you can analyse the deep magic of such a browser where you see how the different resources like images, css etc. etc. are collected, validated, parsed, processed and in the end displayed.
Once the interesting functions are located and a good set of (conditional) breaktpoints is set this could be very useful when it comes to the behaviour of a specific browser.
If that however is too detailed for your context i guess there is no other possibility but to rely on the already given functionality regarding analysing the browsers behaviour like with chromes devTools or the Mozilla plugin Firebug. No doubt this will more and more be integrated in such plugins/ tools like the comment of user BoltClock suggests and it is always worthy to study the functionality of such plugins/ tools to take the biggest possible advance of them.
I have a small website developed using VS2005 and mySQl, it's just 2 webforms and login page.
During the development and testing phase, me and my customer were using IE6, and it was looking fine, we didn't test with other browsers because it's a small application, and just a add-in for large desktop application.
The customer informed me that site doesn't like the same when he installed IE7, for example I have a webfrom that show a page with Gridview that has multiply pages(AllowPaging=On), it doesn't look fine in IE7 and I can't navigate to other pages in Gridview, but it was working fine with IE6, and there's no complicated things, just plan GridView with small formatting.
I installed IE8 and doesn't look fine with it too, even in compatibility mood.
Have anyone faced the same problem?, and what should be the quickest or best solution for that?.
I know, I SHOULD NEVER USE WEBFORMS AGAIN.
The only reason for a difference in look between the browser versions is your styling and doctype.
Start with setting a doctype to run in quirks mode. You can get information about it here.
After that, see if things improve. If not, I would start ripping out any css/styles/themes you may be using. Then build it back up using normal CSS.
Incidentally, web forms isn't the problem in this case; it's a styling issue.
as Chris mentioned, add to that that browsers have really some annoying differences that makes you pull your hair sometimes, and 90 % of the time it is related to CSS.
so what i suggest is the following
use a tool called IE Tester, it is amazing tool that let you test your sites in all IE versions.
Use conditional command for targeting IE specific version if some CSS rule is wrong.
we use this tool http://rafael.adm.br/css_browser_selector/ it is really amazing it let you define css rules for each browser without hacking or conditional statement, but the down side it is Javascript dependent, but we had no complains.
also this script http://dean.edwards.name/IE7/ which is brilliant, it will let IE 6 behave like IE 7 which will save you tons of problems, again it is Java Script dependent.
Avoid Hacks as much as possible, the above methods will help you a lot.
hope this helps.
Short version: What is the cleanest and most maintainable technique for consistant presentation and AJAX function across all browsers used by both web developers and web developers' end-users?
IE 6, 7, 8
Firefox 2, 3
Safari
Google Chrome
Opera
Long version: I wrote a web app aimed at other web developers. I want my app to support the major web browsers (plus Google Chrome) in both presentation and AJAX behavior.
I began on Firefox/Firebug, then added conditional comments for a consistent styling under IE 6 and 7. Next, to my amazement, I discovered that jQuery does not behave identically in IE; so I changed my Javascript to be portable on FF and IE using conditionals and less pure jQuery.
Today, I started testing on Webkit and Google Chrome and discovered that, not only are the styles inconsistant with both FF and IE, but Javascript is not executing at all, probably due to a syntax or parse error. I expected some CSS work, but now I have more Javascript debugging to do! At this point, I want to step back and think before writing piles of special cases for all situations.
I am not looking for a silver bullet, just best practices to keep things as understandable and maintainable as possible. I prefer if this works with no server-side intelligence; however if there is a advantage to, for example, check the user-agent and then return different files to different browsers, that is fine if the total comprehensibility and maintainability of the web app is lower. Thank you all very much!
I am in a similar situation, working on a web app that is targeted at IT professionals, and required to support the same set of browsers, minus Opera.
Some general things I've learned so far:
Test often, in as many of your target browsers as you can. Make sure you have time for this in your development schedule.
Toolkits can get you part of the way to cross-browser support, but will eventually miss something on some browser. Plan some time for debugging and researching fixes for specific browsers.
If you need something that's not in a toolkit and can't find a free code snippet, invest some time to write utility functions that encapsulate the browser-dependent behavior.
Educate yourself about known browser bugs, so that you can steer your implementation around them.
A few more-specific things I've learned:
Use conditional code based on the user-agent only as a last resort, because different generations of the "same" browser may have different features. Instead, test for standards-compliant behavior first — e.g., if(node.addEventListener)..., then common non-standard functions — e.g., if(window.attachEvent)..., and then, if you must, look at the user-agent for a specific browser type & version number.
Knowing when the DOM is 'ready' for script access is different in just about every browser. A good toolkit will abstract this for you.
Event handlers are different in just about every browser. A good toolkit will abstract this for you.
Creating DOM elements, particularly form controls or elements with attributes, can be tricky with document.createElement and element.setAttribute. While not standard (and kinda yucky), using node.innerHTML with strings that contain bits of HTML seems to be more reliable across browser types. I have yet to find a toolkit that will let you use element.setAttribute to add a 'name' to a form element in IE.
CSS differences (and bugs) are just as important as JS differences.
The 'core' Javascript features (String, Date, RegExp, Array functions) seem to be pretty reliable and consistent across browsers, especially relative to the DOM/CSS/Window functions. There's some small joy in the fact that the language isn't entirely different on every platform. :-)
I haven't really run into any Chrome-specific JS bugs, but it's always one of the first browsers I test.
HTH
Chrome is actually a little different to Safari, it uses a completely different javascript implementation and problems have been reported with both prototype and jquery. I wouldn't worry about it too much for now, it's still an early beta version of the browser and such inconsistencies will probably be treated as bugs. Here's the bug report.
One "silver bullet" you may consider turning to is Google Web Toolkit (GWT).
I believe it supports all the browsers you are interested in, and gives you the ability to code your UI in a Java-compatible IDE such as Eclipse. The advantage of this is you can use IDE tools for code completion and compile-time error checking, which greatly improves development on large-scale UI projects.
If you use GWT UI components, it will hide a lot of browser-specific nastiness from having to be dealt with, but when you compile, will create a compact, deploy file for each browser platform. This way you never download any IE-specific code if you are viewing the app in Firefox. You will also have a client-side stub generated which will load the appropriate compiled bundle of JS. To sweeten the deal, these files are cacheable, so perceived performance is generally improved for returning visitors.
The landscape has evolved considerably to accommodate cross-browser development. jQuery, Prototype and other frameworks exist for cross-browser Javascript. CSS resets are good for starting on a common blank canvas for all browsers. BluePrint and 960 are both CSS frameworks to help with layouts using CSS grid layouts techniques that seems to be getting very popular these days.
As for other CSS quirks across the different browsers, there is no holy grail here and the only option is to test you website across different browsers and use this awesome resource and definitely join a mailing list to save up soem time.
If you are working on high volume production site then you can use a service like browsercam.com in the end game to ensure the site doesn't break horribly in some browser.
Lastly, don't try to make the site look the same in every browser. Your primary design should target IE/FF and you should be okay with reasonable compromises on others. Use the graded browser chart to narrow in on browser support.
As for best practices, starting using wireframes on blank paper or a service like Balsamiq mockups. I am still surprised how many developers start with an editor instead of a wireframe but then again I only switched a year back before realizing how big a time saver it is. Have clean seperation of layout (HTML), presentation (CSS) and behaviors (Javascript). There should be no styling elements in HTML, no presenation in Javascript (use .addClass('highlight') instead of .css({'background-color': 'red'});).
If you are not familiar with any of the bold terms in this post, Googling them should be fruitful for your web development career and productivity.
If you're starting from a base reset or framework and have accounted for IE and it's still all freaky, you may want to recheck the following:
Everything validates? CSS and HTML?
Any broken links to an included file (js, css, etc?). In Chrome/Safari, if your stylesheet link is busted, all of your links might end up red. (something to do with the default 404 styling I think)
Any odd requirements of your js plugins that you might be using? (does the css file have to come before the js file, like with jquery.thickbox?)
For UI, check out Ext.
It's great as a standalone library, though it can also be used with jQuery, YUI, Prototype and GWT.
Samples: http://extjs.com/deploy/dev/examples/samples.html
I've found four things helpful in developing JavaScript applications:
Feature detection
Libraries
Iterative Development using Virtualization
JavaScript: The Definitive Guide, Douglas Crockford & John Resig
Feature Detection
Use reflection to ask if the browser supports the desired feature. If you want to know what event handling a browser supports, you can if(el.addEventHandler) for W3C compliance, if(el.attachEvent) for the IE-type, and finally fall back on el.['onSomeEvent'].
ONE BIG BUT!
Browsers sometimes lie about what features they support. I can't remember, but I ran into an issues where Firefox implemented a DOM feature, but would return false if you tested for that feature!
Libraries
Since you're already working with jQuery, I'll save the explanation. But if you're running into problems you may want to consider YUI for it's wonderful cross-browser compatibility. They even work together.
Iterative Development with Virtualization
Perhaps my best advice: Run all your test environment's at once. Get a Linux distro, Compiz Fusion and a bunch of RAM. Download a copy of either VMWare's VMWare Server or Sun's Virtual Box and install a few operating systems. Get images for Windows XP, Windows Vista and Mac OS X.
The basic idea is this: Compiz Fusion gives you 4 Desktops mapped onto a Cube. 1 of these desktops is your Linux computer, the next your Virtutual Windows XP box, the one after that Vista, the last Mac OS X. After writing some code, you alt-tab into virtual computer and check out your work. Plus it looks awesome.
JavaScript: The Definitive Guide, Douglas Crockford & John Resig
These three sources provide most of my information for JavaScript development. The Definitive guide is perhaps the best reference book for JavaScript.
Douglas Crockford is a JavaScript guru (I hate the word) at Yahoo. Lookup his series "Douglas Crockford Theory of the DOM", "Douglas Crockford Advanced JavaScript", "Douglas Crockford Theory of the Dom", and ""Douglas Crockford The Good Parts" on Yahoo! Videos.
John Resig (as you know) wrote jQuery. His website at ejohn.org contains a wealth of JavaScript information, and if you dig around on Google you'll find he's given a number of presentations on defensive JavaScript techniques.
... Good luck!
Just so you've got one less browser to worry about, Chrome uses the same rendering engine as Safari. So if it works in Safari, it should work exactly the same in Chrome.
See this post on Matt Cutts' blog.
Google Chrome uses WebKit for rendering, which is the same rendering engine as Apple’s Safari browser, so if your site is compatible with Safari it should work great in Chrome.
Update: Looks like this is now out-dated info. Please see Vox's comment on this answer.
If your very top priority is exactly consistent presentation on all the browsers listed with no disparities, you should probably be looking at AS3 and Flex.
Personally, I use Mootools as a simple lightweight javascript framework. It is simple to use and supports all the browsers above (except Chrome, but that seems to work too as far as I can tell).
Also, to ensure consistency across the browsers, I get a feature/style/behaviour/etc. to work in one browser first (usually Firefox 3 with firebug), then immediately check to make sure it works in all the other browsers (leaving IE6 for last). If it doesn't, I inveset the time to fix it right away, because otherwise I know I won't have time later (in my experience, getting things to work cross-browser takes about 50% of my dev. time ;-) )
Validating your javascript with a "good parts" + browser on JsLint.com makes it less likely to have JavaScripts behaving differently in FF, Safari etc.
Otherwise - using standards and validating your code as well as building on existing techniques like jQuery should make your site behave the same in all browsers except IE - and there's no magic recipe for IE - it's just bugs everywhere...