The returned node list is ordered. A quick test proved it:

    document.querySelectorAll(&quot;body, head&quot;)[0]; //Returned [object HTMLHeadElement]

Obviously, the `&lt;head&gt;` tag appears before `&lt;body&gt;` in a HTML document. The first element of the NodeList is also a `&lt;head&gt;` element, even if the selector shows `body` before `head.


From http://www.w3.org/TR/selectors-api/#queryselectorall:

&gt; The `querySelectorAll()` method on the NodeSelector interface must, when
&gt; invoked, return a NodeList containing all of the matching Element
&gt; nodes within the node’s subtrees, **in document order**. If there are no
&gt; such nodes, the method must return an empty NodeList.


Working on Ec2 on AWS.

I have installed Node.js and it works fine.

But the problem arises when trying to install npm.

I am using the following command to install it:

    sudo curl http://npmjs.org/install.sh | sh

But the install seems to freeze...
I get &quot;fetching: http://registry.npmjs.org/npm/-/npm-1.0.106.tgz&quot; at the prompt and it stays on like this.

Have any idea what is going on here?

Installing NPM on AWS EC2

Is the sole difference between `boost::scoped_ptr&lt;T&gt;` and `std::unique_ptr&lt;T&gt;` the fact that `std::unique_ptr&lt;T&gt;` has move semantics whereas `boost::scoped_ptr&lt;T&gt;` is just a get/reset smart pointer?

Difference between boost::scoped_ptr&lt;T&gt; and std::unique_ptr&lt;T&gt;

I&#39;m trying to make a js code that works with multiple pages.
I&#39;m trying to use querySelectorAll() to obtain the elements form the DOM.

I need the elements to be ordered. In order to do that I may use xPath or selectors (I&#39;d prefer to use selectors but xPath is also ok). The problem is:  
Are the elements in the NodeList returned by querySelectorAll() ordered against the order that the tags appear in the HTML?




Note: I&#39;d like to add the tag: querySelectorAll

Using querySelectorAll(). Is the result returned by the method ordered?

I'm trying to make a js code that works with multiple pages.
I'm trying to use querySelectorAll() to obtain the elements form the DOM.
I need the elements to be ordered. In order to do that I may use xPath or selectors (I'd prefer to use selectors but xPath is also ok). The problem is: 
Are the elements in the NodeList returned by querySelectorAll() ordered against the order that the tags appear in the HTML?
Note: I'd like to add the tag: querySelectorAll

I want to add codes inside disable() function to disable dragging and zooming in Google maps API v3 by clicking on &#39;disable&#39; button. 

    &lt;script type=&quot;text/javascript&quot;&gt;
       var map;

      function initialize() {
    var uluru = new google.maps.LatLng(21, 57);
    map = new google.maps.Map(document.getElementById(&quot;map&quot;), {
      zoom: 6,
      center: uluru,
      mapTypeId: google.maps.MapTypeId.HYBRID
    });
    }


    function disable(){

    }

    &lt;/script&gt;


    &lt;body onload=&quot;initialize()&quot; &gt;

	   &lt;input type=&quot;button&quot; id=&quot;next&quot; value=&quot;disableZoomDrag&quot; onclick=&quot;disable()&quot;&gt;

    &lt;/body&gt;


disable zooming dragging in Google maps by clicking on a button

What is the difference (if there is any) between

    x = Array()

and

    x = new Array()

Which one should I use?

Array() vs new Array()

# DO YOU KNOW SOME MORE BEST PRACTICES FOR CANVAS?? 

## Please add to this thread what you know, have learned, or have read online any and all Canvas best practices, tips/tricks for performance

With Canvas being still very new to internet, and no signs of it ever getting old that I can see in the future, there are not too many documented &quot;best practices&quot; or other really important tips that are a &#39;must know&#39; for developing with it in any one particular place. Things like this are scattered around and many times on lesser known sites. 

**There&#39;s so many things that people need to know about, and still so much to learn about too.** 

----------


I wanted to share some things to help people who are learning Canvas and maybe some who already know it quite well and am hoping to get some feedback from others about what they feel are some best practices or other tips and tricks for working with Canvas in HTML5. 

I want to start off with one I personally found to be quite a useful yet surprisingly uncommon thing for developers to do.

# 1. Indent your code

Just as you would any other time, in any other language whatever the case may be. It has been a best practice for everything else, and I have come to find that in a complex canvas app, things can get a little confusing when dealing with several different contexts and saved/restore states. Not to mention the code is just more readable and overall cleaner looking too. 

For example:

    ...
    // Try to tell me this doesn&#39;t make sense to do
    ctx.fillStyle = &#39;red&#39;;
    ctx.fill();
    ctx.save();
        if (thing &lt; 3) {
            // indenting
            ctx.beginPath();
                ctx.arc(2, 6, 11, 0, Math.PI*2, true);
            ctx.closePath();
            ctx.beginPath();
                ctx.moveTo(20, 40);
                ctx.lineTo(10, 200);
                ctx.moveTo(20, 40);
                ctx.lineTo(100, 40);
            ctx.closePath();
            ctx.save();
                ctx.fillStyle = &#39;blue&#39;
                ctx.fill();
            ctx.restore();
        } else { 
            // no indenting
            ctx.drawImage(img, 0, 0, 200, 200);
            ctx.save();
            ctx.shadowBlur();
            ctx.beginPath();
            ctx.arc(2, 60, 10, 0, Math.PI*2, false);
            ctx.closePath();
            ctx.fillStyle &#39;green&#39;;
            ctx.fill();
            ctx.restore();
        }
    ctx.restore();
    ctx.drawRect();
    ctx.fill();
    ...

Is the IF statement not easier and cleaner to read and know what is what immediately going on than the ELSE statement in this? Can you see what I&#39;m saying here? I think this should be a method that developers should continue to practice just as they would when writing plain &#39;ol javascript or any other language even.


# Use requestAnimationFrame instead of setInterval / setTimeout

setInterval and setTimeout were never intended to be used as animation timers, they&#39;re just generic methods for calling functions after a time delay.  If you set an interval for 20ms in the future, but your queue of functions takes longer than that to execute, your timer won&#39;t fire until after these functions have completed.  That could be a while, which isn&#39;t ideal where animation is concerned. **RequestAnimationFrame** is a method which tells the browser that an animation is taking place, so it can optimize repaints accordingly.  It also throttles the animation for inactive tabs, so it won&#39;t kill your mobile device&#39;s battery if you leave it open in the background.

Nicholas Zakas wrote a hugely detailed and informative [article about requestAnimationFrame](http://www.nczonline.net/blog/2011/05/03/better-javascript-animations-with-requestanimationframe/) on his blog which is well worth reading.  If you want some hard and fast implementation instructions, then [Paul Irish has written a requestAnimationFrame shim](http://paulirish.com/2011/requestanimationframe-for-smart-animating/) – this is what I&#39;ve used in every one of the Canvas apps I have made until recently.

## ACTUALLY

Even better than using requestAnimationFrame in place of setTimeout and setInterval, Joe Lambert has written a [NEW and improved shim](http://blog.joelambert.co.uk/2011/06/01/a-better-settimeoutsetinterval/) called requestInterval and requestTimeout, which he explains what issues exist when using requestAnimFrame.
You can view the [gist of the script](https://gist.github.com/1002116#file_request_interval.js).

## ACTUALLY x2

Now that all the browsers have caught up on the spec for this, there has been an [update to the requestAnimFrame() polyfill](http://my.opera.com/emoller/blog/2011/12/20/requestanimationframe-for-smart-er-animating), one which will probably remain the one to use to cover all vendors. 


# Use more than one canvas 

A technique for animation-heavy games which [@nicolahibbert](https://twitter.com/nicolahibbert) wrote about in a [post of hers on optimizing Canvas games](http://nicolahibbert.com/optimising-html5-canvas-games/) mentions that it may be better to use multiple canvasses layered on top of one another rather than do everything in a single canvas. Nicola explains that &quot;drawing too many pixels to the same canvas at the same time will cause your frame rate to fall through the floor. Take Breakout for example. Trying to draw the bricks, the ball, the paddle, any power-ups or weapons, and then each star in the background – this simply won&#39;t work, it takes too long to execute each of these instructions in turn. By splitting the starfield and the rest of the game onto separate canvases, you are able to ensure a decent framerate.&quot;

## Render Elements Off-screen

I have had to do this for a few apps I&#39;ve made including [Samsung&#39;s Olympic Genome Project facebook app][1]. It&#39;s an extremely useful thing to know and to make use of whether it&#39;s needed or not. It decreases load time immensely, plus it can be a really useful technique to load images off screen since they can sometimes take a while.

    var tmpCanvas = document.createElement(&#39;canvas&#39;),
        tmpCtx = tmpCanvas.getContext(&#39;2d&#39;),
        img = document.createElement(&#39;img&#39;);
    
    img.onload = function() {
        tmpCtx.drawImage(thumbImg, 0, 0, 200, 200);
    };
    img.src = &#39;/some/image/source.png&#39;;

Notice that the src of the image is set after it is loaded. This is a key thing to remember to do too. Once the images are done loading and drawn into these temp canvases, you can then draw them to your main canvas by using the same ctx.drawImage(), but instead of putting the image as the first argument, you use &#39;tmpCtx.canvas&#39; to reference the temp canvas.


### Other tips, tricks and resources

 - **[Canvas test cases](http://philip.html5.org/tests/canvas/suite/tests/)**
 - **[Some more canvas and JS tests](http://kangax.github.com/jstests/)**
 - **[HTML5Rocks performance Improving](http://www.html5rocks.com/en/tutorials/canvas/performance/)**
 - **[requestAnimFrame to Optimize Dragging Events](http://blog.digitalbackcountry.com/2012/05/using-requestanimationframe-to-optimize-dragging-events/)

### Canvas has a back-reference

The 2d context has a back reference to it&#39;s associated DOM element:

    var ctx = doc.getElementById(&#39;canvas&#39;).getContext(&#39;2d&#39;);
    console.log(ctx.canvas);    // HTMLCanvasElement



I&#39;d love to hear more from other people on this. I am working on making a list of things that we should standardize to add a new section to my company&#39;s [Front-end Code Standards and Best Practices](http://na.standards.com/standards). I&#39;d love to get as much feedback on this as I can.


  [1]: http://www.facebook.com/samsunggenomeproject/app_197458140327772

HTML5 Canvas Performance and Optimization Tips, Tricks and Coding Best Practices

I have run into an odd situation. I&#39;m writing a JavaScript bookmarklet that will allow users to click and share external websites to our website very easily and quickly. It simply get&#39;s the title, page URL, and if they&#39;ve selected any text on the page, it grabs it too.

The problem is it doesn&#39;t work with external domains for some reason, so if we use it internally we end up with a share window with the URL formatted like this:

http://internaldomain.com/sharetool.php?shareid=http://internaldomain.com/anotheroddpage.html&amp;title=....

That works just fine, BUT if we try to use an external domain and end up with a URL formatted like this:

http://internaldomain.com/sharetool.php?shareid=http://externaldomain.com/coolpagetoshare.html&amp;title=...

Then we get a *Forbidden Error* on our page and can&#39;t load it... If we manually remove the `http://` from the externaldomain address, it loads just fine again.

So.. I&#39;m thinking the best solution to get around this problem is to modify the JavaScript bookmarklet to remove the `http` as it&#39;s loading the window. Here is how my current bookmarklet looks:

    javascript:var d=document,w=window,e=w.getSelection,k=d.getSelection,x=d.selection,s=(e?e():(k)?k():(x?x.createRange().text:0)),f=&#39;http://internaldomain.com/sharetool.php&#39;,l=d.location,e=encodeURIComponent,u=f+&#39;?u=&#39;+e(l.href)+

As you can see, `e(l.href)` is where the URL is passed.

How can I modify that so it removes the external domains `http://`?



How to remove &#39;http://&#39; from a URL in JavaScript

What is the equivalent code of `window[&quot;functionName&quot;](arguments)` in NodeJS server-side?




Equivalent of &quot;window[&quot;functionName&quot;](arguments)&quot; in server-side

I am using window.print() for printing page, but I got header and footer contains page title, file path, page number and date. How to remove them? 

I tried print stylesheet also.


    #header, #nav, .noprint
    {
    display: none;
    }

Please help. Thanks.

Remove header and footer from window.print()

Is it possible to override the display property with its default value? For example if I have set it to none in one style, and I want to override it in a different with its default.

Or is the only way to find out what the default of that element is and then set it to that? Would like to not have to know if the element is usually block, inline or whichever...

Reset CSS display property to default value

I have a table with 100% width. If I put `&lt;td&gt;`s in it, they get spread out with equal length columns. However, I want all the columns except last to have as small a width as possible, without wrapping text.

What I did first was that I set `width=&quot;1px&quot;` in all `&lt;td&gt;`s except last (although deprecated, but the `style=&quot;width:1px&quot;` didn&#39;t have any effect), which worked fine until I had multi-word data in the column. In that case, to keep the length as small as possible, it wrapped my text.

Let me demonstrate. Imagine this table:

    ---------------------------------------------------------------------------------
    element1 | data      | junk here   | last column
    ---------------------------------------------------------------------------------
    elem     | more data | other stuff | again, last column
    ---------------------------------------------------------------------------------
    more     | of        | these       | rows
    ---------------------------------------------------------------------------------

No matter what I try, what I keep getting is either this:

    ---------------------------------------------------------------------------------
    element1         | data             | junk here        | last column
    ---------------------------------------------------------------------------------
    elem             | more data        | other stuff      | again, last column
    ---------------------------------------------------------------------------------
    more             | of               | these            | rows
    ---------------------------------------------------------------------------------

or (even though I set `style=&quot;whitespace-wrap:nowrap&quot;`) this:

    ---------------------------------------------------------------------------------
             |      | junk  | last
    element1 | data |       | 
             |      | here  | column
    ---------------------------------------------------------------------------------
             | more | other | again,
    elem     |      |       | last
             | data | stuff | column
    ---------------------------------------------------------------------------------
    more     | of   | these | rows
    ---------------------------------------------------------------------------------

I want to get the table I presented first. How do I achieve this? (I&#39;d rather stick to standard and using CSS. I honestly don&#39;t care if IE hasn&#39;t implemented part of the standard either)

More explanation: What I need is to keep the columns as short as possible without wrapping words (last column should be as large as it needs to make the table width actually reach 100%). If you know LaTeX, what I want is how tables naturally appear in LaTeX when you set their width to 100%.

Note: I found [this](https://stackoverflow.com/questions/1060933/how-to-make-last-cell-of-a-row-in-a-table-occupy-all-remaining-width) but it still gives me the same as last table.

How do I set the table cell widths to minimum except last column?

I am writing a page where I need an html table to maintain a set size. I need the headers at the top of the table to stay there at all times but I also need the body of the table to scroll no matter how many rows are added to the table. 

I want it to look like method 2 in this url: [http://www.cssplay.co.uk/menu/tablescroll.html][1]


  [1]: http://www.cssplay.co.uk/menu/tablescroll.html

I have tried doing this but no scrollbar appears:

&lt;!-- begin snippet: js hide: false console: true babel: false --&gt;

&lt;!-- language: lang-css --&gt;

    tbody {
      height: 80em;
      overflow: scroll;
    }

&lt;!-- language: lang-html --&gt;

    &lt;table border=1 id=&quot;qandatbl&quot; align=&quot;center&quot;&gt;
      &lt;tr&gt;
        &lt;th class=&quot;col1&quot;&gt;Question No&lt;/th&gt;
        &lt;th class=&quot;col2&quot;&gt;Option Type&lt;/th&gt;
        &lt;th class=&quot;col1&quot;&gt;Duration&lt;/th&gt;
      &lt;/tr&gt;

      &lt;tbody&gt;
        &lt;tr&gt;
          &lt;td class=&#39;qid&#39;&gt;&lt;/td&gt;
          &lt;td class=&quot;options&quot;&gt;&lt;/td&gt;
          &lt;td class=&quot;duration&quot;&gt;&lt;/td&gt;
        &lt;/tr&gt;
      &lt;/tbody&gt;
    &lt;/table&gt;

&lt;!-- end snippet --&gt;

How to display scroll bar onto a html table

I want a link that does nothing.  I don&#39;t want this:

`&lt;a href=&quot;#&quot;&gt;`

because then the URL becomes `something.com/whatever/#`.

The only reason I want a link is so the user can see that they can click on the text.  JavaScript is being used to perform some action so I don&#39;t need the link to go anywhere but I need it to look like a link!

I could use some data attribute and tell me CSS to make elements look like links if they have this attribute but it seems a bit overkill.


Make a HTML link that does nothing (literally nothing)

I am trying to create a cascading effect by applying an animation to each child element. I was wondering if there is a better way to do it than this:


	.myClass img:nth-child(1){
		-webkit-animation: myAnimation 0.9s linear forwards;
	}
	.myClass img:nth-child(2){
		-webkit-animation: myAnimation 0.9s linear 0.1s forwards;
	}
	.myClass img:nth-child(3){
		-webkit-animation: myAnimation 0.9s linear 0.2s forwards;
	}
	.myClass img:nth-child(4){
		-webkit-animation: myAnimation 0.9s linear 0.3s forwards;
	}
	.myClass img:nth-child(5){
		-webkit-animation: myAnimation 0.9s linear 0.4s forwards;
	}


and so on...
So basically, I&#39;d like to have an animation starting for each child but with a delay. 
Thanks for any input!

Addition: Maybe I did not properly explain what was my concern: It&#39;s about how to do this no matter how many children I have. How to do this without having to write down the properties for every child... for example, when I don&#39;t know how many children there are going to be. 


CSS Animations with delay for each child element

Is there a CSS selector to select this element by its inline style attribute value?

    &lt;div style=&#39;display:block&#39;&gt;...&lt;/div&gt;

something like

    div[cssAttribute=cssValue]



CSS selector by inline style attribute

Here is my CSS:

    #nav-primary ul li:nth-child(1) a:after { }

Works everywhere now (used [this][1] on my website) except Internet Explorer 8...

Is there possibly a way to use nth-child in IE8?
This is the worst version of this browser... nothing works as it should and I can&#39;t find a way to fix it.

@edit:
Simplified version of what I want to achieve: [http://jsfiddle.net/LvvNL/][2]. Its just a start. CSS will be more complicated so I need to be able to aim every one of this links. Hope adding classes to every link is not the only way

@edit2:
I&#39;ve just noticed that 	

    #nav-primary ul li:nth-child(1) a {
        border-top: 5px solid #144201;
    }

IS actually working in IE8! But this:

	#nav-primary ul li:nth-child(1) a:after {
		content: &quot;Text&quot;;
		display: block;
		font-weight: normal;
		padding-top: 5px;
		font-size: 12px;
		color: #666;
	}

is NOT working. So what is going on?


  [1]: http://code.google.com/p/ie7-js/
  [2]: http://jsfiddle.net/LvvNL/

IE8 :nth-child and :before

Is there a way to style the currently selected `&lt;option&gt;` element in a `&lt;select&gt;` element?

I could then give a background color to the currently selected option element? That way I can style the option that&#39;s currently viewable in the closed dropdown.

CSS :selected pseudo class similar to :checked, but for &lt;option&gt; elements

I&#39;m having a heck of a time with this particular CSS selector which does not want to work when I add `:not(:empty)` to it. It seems to work fine with any combination of the other selectors:

&lt;!-- language: lang-css --&gt;

    input:not(:empty):not(:focus):invalid { border-color: #A22; box-shadow: none }

If I remove the `:not(:empty)` part, it works just fine. Even if I change the selector to `input:not(:empty)` it still won&#39;t select input fields which have text typed into them. Is this broken or am I just not allowed to use `:empty` within a `:not()` selector?

The only other thing I can think of is that browsers are still saying that the element is empty because it has no children, just a &quot;value&quot; per say. Does the `:empty` selector not have separate functionality for an input element versus a regular element? This doesn&#39;t seem probable though because using `:empty` on a field and typing something into it will cause the alternate effects to go away (because it is no longer empty).

Tested in Firefox 8 and Chrome.


:not(:empty) CSS selector is not working?

Is there a way to do a wildcard element name match using `querySelector` or `querySelectorAll`? 

The XML document I&#39;m trying to parse is basically a flat list of properties
 - I need to find elements that have certain strings in their names.
 - I see support for wildcards in attribute queries but not for the elements themselves.


Any solution except going back to using the apparently deprecated XPath (IE9 dropped it) is acceptable.

querySelector, wildcard element match?

I&#39;m trying to use `document.querySelectorAll` for all checkboxes that have the `value` attribute set.

There are other checkboxes on the page that do not have `value` set, and the value is different for each checkbox. The ids and names are not unique though.

Example:
    `&lt;input type=&quot;checkbox&quot; id=&quot;c2&quot; name=&quot;c2&quot; value=&quot;DE039230952&quot;/&gt;`

How do I select just those checkboxes that have values set?

How to use querySelectorAll only for elements that have a specific attribute set?

This seems like something that would have a quick answer, but I can&#39;t find one. Maybe I&#39;m searching the wrong terms? No libraries please, though I don&#39;t need cross-browser fallbacks, I&#39;m targeting all the latest versions on this project. 

I&#39;m getting some elements:

    element = document.querySelectorAll(&quot;.someselector&quot;);

This is working, but how do I now delete these elements? Do I have to loop through them and do the `element.parentNode.removeChild(element);` thing, or is there a simple function I&#39;m missing?

How to remove elements that were fetched using querySelectorAll?

I&#39;ve an element in the DOM:

`&lt;a href=&quot;#&quot; data-a=&quot;1&quot;&gt;Link&lt;/a&gt;`

I want to get this element via its HTML5 custom data attribute `data-a`. So I write JS codes:

`var a = document.querySelector(&#39;a[data-a=1]&#39;);`

But this code doesn&#39;t work and I get an error in browser&#39;s console. (I tested Chrome and Firefox.)

JS code `var a = document.querySelector(&#39;a[data-a=a]&#39;);` doesn&#39;t cause error. So I think the problem is that HTML5&#39;s JS API `document.querySelector` doesn&#39;t support to look for the number value in HTML5 custom data attribute.

Is this a problem of browser implementation bug or a problem of HTML5&#39;s spec relevant to `document.querySelector`?

Then I tested codes below on http://validator.w3.org/:

    &lt;!DOCTYPE html&gt;
    &lt;meta charset=&quot;utf-8&quot;&gt;
    &lt;title&gt;An HTML Document&lt;/title&gt;
    &lt;a href=&quot;#&quot; data-a=&quot;1&quot;&gt;Link&lt;/a&gt;

They&#39;re validated. Since these HTML5 codes are validated. We should can use HTML5&#39;s JS API `document.querySelector` to look for this anchor element via its custom data attribute. But tha fact is that I get error.

Does HTML5&#39;s spec to HTML5 JS API `document.querySelector` say that this method can not look for an HTML5 data custom attribute with a number value? (An HTML5 spec source is wanted.)


Why does JS code &quot;var a = document.querySelector(&#39;a[data-a=1]&#39;);&quot; cause error?

On a page I&#39;m doing I will be ending up with custom `link` elements like this:

    &lt;link rel=&quot;multiply&quot; type=&quot;service/math&quot; src=&quot;path/to/service&quot;&gt;
    &lt;link rel=&quot;substract&quot; type=&quot;service/math&quot; src=&quot;path/to/service&quot;&gt;
    ...

I&#39;m trying to use `querySelectorAll` to retrieve all link elements with a type `service/...` specified and am getting nowhere.

Currently I&#39;m selecting this:

    root.querySelectorAll(&#39;link&#39;);

which gives me all `&lt;link&gt;` elements when I only want the ones with type `service/.*`


**Questions:**  
Can I add a regex to a QSA selector? If so, how to do it?

Content Type	Original Author	Original Content on Stackoverflow
Question	brunoais	View Question on Stackoverflow
Solution 1 - Javascript	Rob W	View Answer on Stackoverflow

Using querySelectorAll(). Is the result returned by the method ordered?

Javascript Problem Overview

Javascript Solutions

Solution 1 - Javascript

Difference between boost::scoped_ptr<T> and std::unique_ptr<T>

Installing NPM on AWS EC2

Attributions