I had the same question today and was able to find a solution thanks to [Scott Kosman](https://twitter.com/humantorch) [**here**](http://24ways.org/2011/your-jquery-now-with-less-suck/).

Basically the answer is to select IDs individually and then use `.find(...)` for anything below. So taking your example:

    $(&quot;#property [data-role=&#39;content&#39;] .container&quot;);

Changing it to this makes PhpStorm happy and can evidently be [more than twice as fast](http://24ways.org/2011/your-jquery-now-with-less-suck/):

    $(&quot;#property&quot;).find(&quot;[data-role=&#39;content&#39;] .container&quot;);

I believe the difference between the two methods when using recent versions of jQuery and browsers is negligible.  I constructed a test that shows that it is now actually 10% faster to do a combined selector rather than selection on id and then find for a very simple case:

http://jsperf.com/jquery-find-vs-insel

For selection of multiple children by class at any depth, the &quot;find&quot; does appear to be faster:

http://jsperf.com/jquery-find-vs-insel/7

There was some discussion about this on jQuery forums, but its 3 years old:
https://forum.jquery.com/topic/which-jquery-selection-is-efficient
As they point out here, if you are doing a lot of operations on same id selector, the greatest performance improvement is found by caching the top level element.
On the other hand if you are doing just a few selections, there is going to be virtually no performance difference.

Therefor I believe that IntelliJ is overstating the importance of this code style. 

The first question is to hit Alt+Enter, and select the first tip in the list, then hit Enter, you&#39;ll see what it thinks the most efficient way.

I am developing an application for sending SMS. I am storing the current time and showing in the sent history page by retrieving the time from the database. In the sent history page I want to display the time of the message was sent. Here I want to check that the message has been sent today or yesterday or the the day before yesterday like that. If the message was sent yesterday means then I need to display &quot;Yesterday 20:00&quot; like that and even the message was sent yesterday before means &quot;Monday 20:00&quot;. I don&#39;t know how it has to be done. Please help me if anybody knows.

How to find time is today or yesterday in android

I have an iPhone app that uses a `UINavigationController` to present a drill-down interface: First one view, then another, up to four levels deep. I want the first three views restricted to portrait orientation and only the last view should be allowed to rotate to landscape. When returning from the fourth view to the third and the fourth view was in landscape orientation I want everything to rotate back to portrait.

In iOS 5 I simply defined `shouldAutorotateToInterfaceOrientation:` in each of my view controllers to return YES for the allowable orientations. Everything worked as described above, including the return to portrait even if the device was being held in landscape orientation when returning from view controller #4 to #3.

In iOS 6 all view controllers rotate to landscape, breaking those that weren&#39;t meant to. The iOS 6 release notes say 

&gt; More responsibility is moving to the app and the app delegate. Now, iOS containers (such as `UINavigationController`) do not consult their children to determine whether they should autorotate. [...] The system asks the top-most full-screen view controller (typically the root view controller) for its supported interface orientations whenever the device rotates or whenever a view controller is presented with the full-screen modal presentation style. Moreover, the supported orientations are retrieved only if this view controller returns YES from its `shouldAutorotate` method. [...] The system determines whether an orientation is supported by intersecting the value returned by the app’s `supportedInterfaceOrientationsForWindow:` method with the value returned by the `supportedInterfaceOrientations` method of the top-most full-screen controller.

So I subclassed `UINavigationController`, gave my `MainNavigationController` a boolean property `landscapeOK` and used this to return the allowable orientations in `supportedInterfaceOrientations`. Then in each of my view controllers&#39; `viewWillAppear:` methods I have a line like this

        [(MainNavigationController*)[self navigationController] setLandscapeOK:YES];

to tell my `MainNavigationController` the desired behavior.

**Here comes the question:** If I now navigate to my fourth view in portrait mode and turn the phone over it rotates to landscape. Now I press the back button to return to my third view which is supposed to work portrait only. But it doesn&#39;t rotate back. How do I make it do that?

I tried

        [[UIApplication sharedApplication] setStatusBarOrientation:UIInterfaceOrientationPortrait]

in the `viewWillAppear` method of my third view controller, but it doesn&#39;t do anything. Is this the wrong method to call or maybe the wrong place to call it or should I be implementing the whole thing in a totally different way?

 

iOS 6: How do I restrict some views to portrait and allow others to rotate?

I recently upgraded my version of PHPStorm IDE and it now warns me about inefficient jQuery usage.

For example:

    var property_single_location = $(&quot;#property [data-role=&#39;content&#39;] .container&quot;);

Prompts this warning:

&gt; Checks that jQuery selectors are used in an efficient way. It suggests
&gt; to split descendant selectors which are prefaced with ID selector and
&gt; warns about duplicated selectors which could be cached.

So my question is:

&gt; Why is this inefficient and what is the efficient way to do the above selector?

I&#39;d guess at:

    var property_single_location = $(&quot;#property&quot;).find(&quot;[data-role=&#39;content&#39;]&quot;).find(&quot;.container&quot;);

Is this the right way?

Inefficient jQuery usage warnings in PHPStorm IDE

I recently upgraded my version of PHPStorm IDE and it now warns me about inefficient jQuery usage.
For example:
<pre><code class="hljs language-ini">var property_single_location = $("#property [data-role='content'] .container");
</code></pre>
Prompts this warning:
> Checks that jQuery selectors are used in an efficient way. It suggests
> to split descendant selectors which are prefaced with ID selector and
> warns about duplicated selectors which could be cached.
So my question is:
> Why is this inefficient and what is the efficient way to do the above selector?
I'd guess at:
<pre><code class="hljs language-ini">var property_single_location = $("#property").find("[data-role='content']").find(".container");
</code></pre>
Is this the right way?

If I&#39;m working in a TypeScript .ts file, what can I do to get jQuery Intellisense/autocompletion when I type the $ character?

(I&#39;m working in an ASP.NET MVC 3 project in VS 2012.)

How do I get jQuery autocompletion in TypeScript?

I&#39;ve created a page with CSS. Now I must change from my editor to my browser and refresh the full page, just to have a look at every little change. But I don&#39;t want to refresh the page, because I have some animations.

So is there anything which I can use that my site updates automatically after a CSS update?  
Maybe with JavaScript, jQuery, Ajax or something?

Update the CSS of a Website without refreshing the Page

Can someone explain in an easy way how to make jQuery send actual JSON instead of a query string?

    $.ajax({
        url      : url,
        dataType : &#39;json&#39;, // I was pretty sure this would do the trick
        data     : data,
        type     : &#39;POST&#39;,
        complete : callback // etc
    });

This will in fact convert your carefully prepared JSON to a query string. One of the annoying things is that any `array: []` in your object will be converted to `array[]: []`, probably because of limitations of the query sting.

How to send JSON instead of a query string with $.ajax?

&gt; **Possible Duplicate:**  
&gt; [How do JavaScript closures work?](https://stackoverflow.com/questions/111102/how-do-javascript-closures-work)  

&lt;!-- End of automatically inserted text --&gt;

I was playing around with the [Google Closure Compiler][1], putting in random code to see what it would do.

It rewrote one of my functions to look something like this:

    (function(msg) { console.log(msg); })(&quot;Hello World!&quot;);​​​​​​​

Where it appears that `&quot;Hello World&quot;` is the argument passed as `msg` to the anonymous function preceding it. I was looking at it for a moment, and had thought that I had seen something similar in jQuery plugins that look something like:

    (function( $ ) {
      ...
    })(jQuery); 

Which now makes more sense to me, in the scope of conflicts with `$`. But what is the primary reason or purpose for passing arguments into an anonymous function like this? Why wouldn&#39;t you simply define the arguments as variables within the function? Is there any performance or flexibility advantage to writing functions like this?

  [1]: http://closure-compiler.appspot.com/home

What is the purpose of passing arguments to anonymous functions in this manner?

In my HTML5 page, I have a div with `mousemove` event as follows:

	$(&#39;#canvas&#39;).mousemove(function(e){
		xpos = e.offsetX;
		ypos = e.offsetY;
		$(&#39;#mouse&#39;).html(&quot;X : &quot; + xpos + &quot; ; Y : &quot; + ypos);
	});

It works fine with Google Chrome. But in Firefox, both the are giving the value `undefined`. I have checked it by using Firebug, that is, logged the `e` object to console. Both `offsetX` and `offsetY` are found to be `undefined`.

When I searched in Google, there was a solution saying I should use `layerX` and `layerY`, if both `offsetX` and `offsetY` are undefined.
But from Firebug, I was not able to find it. And even I had given it a try like this:

    xpos = (e.offsetX==undefined)?e.layerX:e.offsetX;
    ypos = (e.offsetY==undefined)?e.layerY:e.offsetY;

But that&#39;s also giving `undefined` as values.

I am using the most recent jQuery - v1.8.2. And I am testing in my Firefox v14.0.1

Any ideas or suggestions?

---
**EDIT**

Thanks to dystroy and vusan for helping me. The solution to the above issue is as follows:

**SOLUTION**

    $(&#39;#canvas&#39;).mousemove(function(e){
      $(&#39;#cursor&#39;).show();
      if(e.offsetX==undefined) // this works for Firefox
      {
        xpos = e.pageX-$(&#39;#canvas&#39;).offset().left;
        ypos = e.pageY-$(&#39;#canvas&#39;).offset().top;
      }				
      else                     // works in Google Chrome
      {
        xpos = e.offsetX;
        ypos = e.offsetY;
      }
      $(&#39;#mouse&#39;).html(&quot;X : &quot; + xpos + &quot; ; Y : &quot; + ypos);
    });


HTML5 with jQuery - e.offsetX is undefined in Firefox

`.offset([coordinates])` method set the coordinates of an element but only relative to the document. Then how can I set coordinates of an element but relative to the parent?

I found that `.position()` method get only &quot;top,left&quot; values relative to the parent, but it doesn&#39;t set any values.

I tried with 

    $(&quot;#mydiv&quot;).css({top: 200, left: 200});

but does not work.

In jQuery how can I set &quot;top,left&quot; properties of an element with position values relative to the parent and not the document?

Where this is coming from
-------------------------
When I first learned jQuery, I normally attached events like this:
 
    $(&#39;.my-widget a&#39;).click(function() {
        $(this).toggleClass(&#39;active&#39;);
    });
 
After learning more about selector speed and event delegation, I read in several places that &quot;jQuery event delegation will make your code faster.&quot; So I started to write code like this:
 
    $(&#39;.my-widget&#39;).on(&#39;click&#39;,&#39;a&#39;,function() {
        $(this).toggleClass(&#39;active&#39;);
    });
 
This was also the recommended way to replicate the behavior of the deprecated .live() event. Which is important to me since a lot of my sites dynamically add/remove widgets all the time. The above doesn&#39;t behave exactly like .live() though, since only &lt;a&gt; elements added to the already existing container &#39;.my-widget&#39; will get the behavior. If I dynamically add another block of html after that code has ran, those &lt;a&gt; elements will not get the events bound to them. Like this:
 
    setTimeout(function() {
        $(&#39;body&#39;).append(&#39;&lt;div class=&quot;my-widget&quot;&gt;&lt;a&gt;Click does nothing&lt;/a&gt;&lt;/div&gt;&#39;);
    }, 1000);
&lt;br&gt;
What I want to achieve:
----------------------- 
1. the old behavior of .live() // meaning attaching events to not yet existent elements
2. the benefits of .on()
3. fastest performance to bind events
4. Simple way to manage events
 
I now attach all events like this:

    $(document).on(&#39;click.my-widget-namespace&#39;, &#39;.my-widget a&#39;, function() {
        $(this).toggleClass(&#39;active&#39;);
    });
 
Which seems to meet all my goals. (Yes it&#39;s slower in IE for some reason, no idea why?)
It&#39;s fast because only a single event is tied to a singular element and the secondary selector is only evaluated when the event occurs (please correct me if this is wrong here). The namespace is awesome since it makes it easier to toggle the event listener. 
&lt;br&gt;
&lt;br&gt;
My Solution/Question
--------------------
So I&#39;m starting to think that jQuery events should always be bound to $(document).&lt;br&gt;
**Is there any reason why you would not want to do this?&lt;br&gt;
Could this be considered a best practice? If not, why?**


If you&#39;ve read this whole thing, thank you. I appreciate any/all feedback/insights. 


Assumptions:

1. Using jQuery that supports `.on()` // at least version 1.7
2. You want the the event to be added to dynamically added content
 
Readings/Examples:
 
1. http://24ways.org/2011/your-jquery-now-with-less-suck
2. http://brandonaaron.net/blog/2010/03/4/event-delegation-with-jquery
3. http://www.jasonbuckboyer.com/playground/speed/speed.html
4. http://api.jquery.com/on/

Should all jquery events be bound to $(document)?

I have a `select` field with some options in it. Now I need to select one of those `options` with jQuery. But how can I do that when I only know the `value` of the `option` that must be selected?

I have the following HTML:

    &lt;div class=&quot;id_100&quot;&gt;
      &lt;select&gt;
        &lt;option value=&quot;val1&quot;&gt;Val 1&lt;/option&gt;
        &lt;option value=&quot;val2&quot;&gt;Val 2&lt;/option&gt;
        &lt;option value=&quot;val3&quot;&gt;Val 3&lt;/option&gt;
      &lt;/select&gt;
    &lt;/div&gt;

I need to select the option with value `val2`. How can this be done?

Here&#39;s a demo page:
http://jsfiddle.net/9Stxb/


Set select option &#39;selected&#39;, by value

&gt; **Possible Duplicate:**  
&gt; [jQuery, Select by attribute value, adding new attribute](https://stackoverflow.com/questions/3724245/jquery-select-by-attribute-value-adding-new-attribute)  
&gt; [jQuery - How to select by attribute](https://stackoverflow.com/questions/9210073/jquery-how-to-select-by-attribute)  

&lt;!-- End of automatically inserted text --&gt;

please consider this code:

    &lt;p&gt;11111111111111&lt;/p&gt;
    &lt;p MyTag=&quot;nima&quot;&gt;2222222222&lt;/p&gt;
    &lt;p&gt;33333333333&lt;/p&gt;
    &lt;p MyTag=&quot;Sara&quot;&gt;&gt;4444444444&lt;/p&gt;

how I can select All `p` tag with attribute `MyTag`?

thanks

jQuery : select all element with custom attribute

All right, I wonder if there is a way to make the `:contains()` jQuery&#39;s selector to select elements with **only** the string that is typed in

for example -&lt;br /&gt;

    &lt;p&gt;hello&lt;/p&gt;
    &lt;p&gt;hello world&lt;/p&gt;

    $(&#39;p:contains(&quot;hello&quot;)&#39;).css(&#39;font-weight&#39;, &#39;bold&#39;);

The selector will select both `p` elements and make them bold, but I want it to select only the first one.


Select element by exact match of its content

Here is my Perl and Python script to do some simple text processing from about 21 log files, each about 300&amp;nbsp;KB to 1&amp;nbsp;MB (maximum) x 5 times repeated (total of 125 files, due to the *log* repeated 5 times).

**Python Code** (code modified to use compiled `re` and using `re.I`)

    #!/usr/bin/python

    import re
    import fileinput

    exists_re = re.compile(r&#39;^(.*?) INFO.*Such a record already exists&#39;, re.I)
    location_re = re.compile(r&#39;^AwbLocation (.*?) insert into&#39;, re.I)

    for line in fileinput.input():
        fn = fileinput.filename()
        currline = line.rstrip()

        mprev = exists_re.search(currline)

        if(mprev):
            xlogtime = mprev.group(1)

        mcurr = location_re.search(currline)

        if(mcurr):
            print fn, xlogtime, mcurr.group(1)

**Perl Code**

    #!/usr/bin/perl

    while (&lt;&gt;) {
        chomp;

        if (m/^(.*?) INFO.*Such a record already exists/i) {
            $xlogtime = $1;
        }

        if (m/^AwbLocation (.*?) insert into/i) {
            print &quot;$ARGV $xlogtime $1\n&quot;;
        }
    }

And, on my PC both code generates exactly the same result file of 10,790 lines. And, here is the timing done on Cygwin&#39;s Perl and Python implementations.

    User@UserHP /cygdrive/d/tmp/Clipboard
    # time /tmp/scripts/python/afs/process_file.py *log* *log* *log* *log* *log* &gt;
    summarypy.log

    real    0m8.185s
    user    0m8.018s
    sys     0m0.092s

    User@UserHP /cygdrive/d/tmp/Clipboard
    # time /tmp/scripts/python/afs/process_file.pl *log* *log* *log* *log* *log* &gt;
    summarypl.log

    real    0m1.481s
    user    0m1.294s
    sys     0m0.124s

Originally, it took 10.2 seconds using Python and only 1.9 secs using Perl for this simple text processing.

**(UPDATE) but, after the compiled `re` version of Python, it now takes 8.2 seconds in Python and 1.5 seconds in Perl. Still Perl is much faster.**

Is there a way to improve the speed of Python at all OR it is obvious that Perl will be the speedy one for simple text processing.

By the way this was not the only test I did for simple text processing... And, each different way I make the source code, always always Perl wins by a large margin. And, not once did Python performed better for simple `m/regex/` match and print stuff.

&gt; Please do not suggest to use C, C++, Assembly, other flavours of
&gt; Python, etc.
&gt;
&gt; I am looking for a solution using Standard Python with its built-in
&gt; modules compared against Standard Perl (not even using the modules).
&gt; Boy, I wish to use Python for all my tasks due to its readability, but
&gt; to give up speed, I don&#39;t think so.
&gt;
&gt; So, please suggest how can the code be improved to have comparable
&gt; results with Perl.

**UPDATE: 2012-10-18**

As other users suggested, Perl has its place and Python has its.

So, for this question, one can safely conclude that for simple regex match on each line for hundreds or thousands of text files and writing the results to a file (or printing to screen), **Perl will always, always WIN in performance for this job. It as simple as that.**

Please note that when I say Perl wins in performance... only standard Perl and Python is compared... not resorting to some obscure modules (obscure for a normal user like me) and also not calling C, C++, assembly libraries from Python or Perl. We don&#39;t have time to learn all these extra steps and installation for a simple text matching job.

So, Perl rocks for text processing and regex.

Python has its place to rock in other places.

**Update 2013-05-29:** An excellent article that does similar comparison [is here][1]. Perl again wins for simple text matching... And for more details, read the article.

  [1]: https://stuffivelearned.org/doku.php?id=programming:general:phpvspythonvsperl



Text processing - Python vs Perl performance

How can I check Heap Size (and Used Memory) of a Java Application on Linux through the command line?

I have tried through jmap. But it gives info. about internal memory areas like Eden/ PermGen etc., which is not useful to me. 

I am looking for something like:

 - Max Memory: 1GB
 - Min Memory: 256 MB
 - Heap Memory: 700 MB
 - Used Memory: 460 MB

That&#39;s all. I know that I can see this in JConsole etc., but I need to do it via command-line. (can&#39;t enable JMX etc.)

How to find Java Heap Size and Memory Used (Linux)?

Is there any good way to get the remaining memory available to the JVM at run time? The use case of this would be to have web services which fail gracefully when they are nearing their memory limits by refusing new connections with a nice error message &quot;too many people using this, try again later&quot;, rather than dying abruptly with an OutOfMemory error.

Note this has nothing to do with calculating/estimating the cost of each object beforehand. In principle I could estimate how much memory my objects take and refuse new connections based on that estimate, but that seems kind of hacky/fragile.



Java get available memory

I have Symfony2 running on an Ubuntu Server 12.04 (64-bit) VM (VirtualBox).  The host is a MacBook pro.  For some reason I am getting really long request times in development mode (app_dev.php).  I know its slower in dev mode, but I&#39;m talking 5-7 seconds per request (sometimes even slower).  On my Mac I get request times of 200ms or so in development mode.

After looking at my timeline in the Symfony2 profiler, I noticed that ~95% of the request time is &quot;initialization time&quot;.  What is this?  What are some reasons it could be so slow?

This issue only applies to Symfony2 in dev mode, not any other sites I&#39;m running on the VM, and not even to Symfony2 in production mode.

I saw this (http://stackoverflow.com/questions/11162429/whats-included-in-the-initialization-time-in-the-symfony2-web-profiler), but it doesn&#39;t seem to answer my questions.

Symfony2 Slow Initialization Time

HTML5 websockets currently use a form of TCP communication. However, for real-time games, TCP just won&#39;t cut it (and is great reason to use some other platform, like native). As I probably need UDP to continue a project, I&#39;d like to know if the specs for HTML6 or whatever will support UDP?


Also, are there any reliable benchmarks for WebSockets that would compare the WS protocol to a  low-level, direct socket protocol?

Content Type	Original Author	Original Content on Stackoverflow
Question	Scott	View Question on Stackoverflow
Solution 1 - Jquery	MikeSchinkel	View Answer on Stackoverflow
Solution 2 - Jquery	Leonya	View Answer on Stackoverflow
Solution 3 - Jquery	UnixAgain	View Answer on Stackoverflow

Inefficient jQuery usage warnings in PHPStorm IDE

Jquery Problem Overview

Jquery Solutions

Solution 1 - Jquery

Solution 2 - Jquery

Solution 3 - Jquery

iOS 6: How do I restrict some views to portrait and allow others to rotate?

How to find time is today or yesterday in android

Attributions