jquery and javascript native - javascript

am currently studying jquery, can someone tell me the things that javascript native can do which jquery cannot ?

In short: nothing
jQuery is an abstraction layer on top of plain JavaScript, it is JavaScript, it just adds a bunch of shortcuts to common tasks, usually in a highly optimized and cross-browser way.
It doesn't take anything away, you can mix and match all you want, jQuery simply adds to your options.
I'd take a look at the jQuery getting started documentation for more questions you might have like this.

jQuery is a library for Javascript which adds additional features.
It doesn't replace anything.

None i think. But there maybe some things that jQuery can do but JavaScript cannot.

Related

why jquery for modifying style properties?

when it comes to modifying formatting and layouts (style sheets) why would jquery be more advantageous compared to plain javascript??
plain javascript already provides functions like "getelementsbyclassname" or "getelementsbyid" to get a handle for element objects, then why use the jquery interface?
i've read it's "easier"... exactly how?
"more efficient"? but it adds another layer of abstraction...
sure the library is quite easy to download the library since it's CDN-ed, but i want something that's even more minimalistic.
EDIT (after hearing ohcibi's response):
ANOTHER QUESTION: if i'm only concerned about modifying style sheets, would sizzle.js be a more minimalistic option? is it's implementation (as far as it's scope go) as complete as jQuery? does it execute faster?
To put it simply: Cross-browser compatibility, ease of writing/reading, more efficient coding, ubiquitous use.
Also, it doesn't replace ALL javascript. You can use javascript with it if you like or for some simple things that are recognized (more or less) universally by browsers.
Just to restate: more efficient coding.
It's not more minimalistic to write everything in plain js for all the different browser quirks that jquery does for you already. But feel free to do so if you have the time.
getElementsByClassname and so on do not provide full CSS3 featured selectors. Plus they are not 100% browser compatible.
If youre only interested into these selectors. Try sizzle.js, its what jQuery uses for the selection of elements.

Is it considered Bad Idea to Edit the orginal JQuery File?

We have Tabs-Menu controls which rely on jQuery library and the dev-manager insist that i should get the functions that controls are using into a separate java-script file so we don't have to reference/rely on the whole jQuery, so it made me wonder.. is it a bad idea to edit the jQuery files ?
Yes it is a very bad idea. It would be a nightmare to maintain with all the bug fixes and feature changes the jQuery team would make.
You should write plugins to modify the behavior as you want.
The gzipped production version of jQuery is 31K. Not only is this an unmaintainable idea, but this is a pre-optimization. Any images beyond tiny PNGs or GIFs will likely be as large or larger than the entire jQuery library.
Additionally, this is time that could be spent addressing actual problems. I don't know what sort of userbase you're targeting, but unless every one of your users is on dialup, 31K will take no time at all to download.
is it a bad idea to edit the jQuery files ?
Yes. If you edit the core jQuery library, you make it much more difficult to use future versions of jQuery, which may include important new features, bug fixes, etc. If you make your changes in plugins, as you should, you can just drop in the new versions of jQuery when they're released.
Well I'd say it's a pretty bad idea. You really want the responsibility of maintaining the mess you have left after chopping it out? Are you an expert on the jQuery library? Do you understand all of the side effects? You would be better off rewriting portions of your Tabs-Menu controls without jQuery than trying to chop out bits of jQuery. I presume that the issue is that you don't want the "overhead" of including a relatively large script for a small set of features. This is unfortunately the way of jQuery. Either
Accept that you have to use jQuery, and make the most of having it referenced
Rewrite your Tabs-Menu controls without jQuery
any other option is going to be painful. Insist that your dev-manager reads the answers to the question.

Creating a jQuery Plugin out of jQuery code

Here's my problem: I've got this nice Office Minibar implementation which I want to use on my project. However, I need to apply the Jquery code to dynamically created textarea elements, hence requiring the use of
$("#textarea_id").minibar(); //minibar() applies the minibar to the selected textarea element
However, i'm at a complete loss on how to do it. Any help would be great appreciated. The Minibar coding is fairly simple:
http://www.jankoatwarpspeed.com/post/2010/05/23/microsoft-office-minibar-jQuery-CSS3.aspx
Start out reading the jQuery plugin authoring guide. It does a really good job of walking you through things. If you want to cut to the chase, read the summary and best practices section.
Basically, it'll look like this:
(function($){
$.fn.minibar = function () {
// minibar initialization code here
};
})(jQuery);
jQuery's plugin authoring is a great starting point.
I also agree that the Plugin Authoring tool is a good start.
Also there is a Jquery Plugin Skeleton that provides a commonly used plugin pattern.
I noticed that in your code you have static ids and markup. It may be better to create these elements dynamically so people that use your plugin don't have to add them and there are no id or class name conflicts.

When to use Vanilla JavaScript vs. jQuery?

I have noticed while monitoring/attempting to answer common jQuery questions, that there are certain practices using javascript, instead of jQuery, that actually enable you to write less and do ... well the same amount. And may also yield performance benefits.
A specific example
$(this) vs this
Inside a click event referencing the clicked objects id
jQuery
$(this).attr("id");
Javascript
this.id;
Are there any other common practices like this? Where certain Javascript operations could be accomplished easier, without bringing jQuery into the mix. Or is this a rare case? (of a jQuery "shortcut" actually requiring more code)
EDIT : While I appreciate the answers regarding jQuery vs. plain javascript performance, I am actually looking for much more quantitative answers. While using jQuery, instances where one would actually be better off (readability/compactness) to use plain javascript instead of using $(). In addition to the example I gave in my original question.
this.id (as you know)
this.value (on most input types. only issues I know are IE when a <select> doesn't have value properties set on its <option> elements, or radio inputs in Safari.)
this.className to get or set an entire "class" property
this.selectedIndex against a <select> to get the selected index
this.options against a <select> to get a list of <option> elements
this.text against an <option> to get its text content
this.rows against a <table> to get a collection of <tr> elements
this.cells against a <tr> to get its cells (td & th)
this.parentNode to get a direct parent
this.checked to get the checked state of a checkbox Thanks #Tim Down
this.selected to get the selected state of an option Thanks #Tim Down
this.disabled to get the disabled state of an input Thanks #Tim Down
this.readOnly to get the readOnly state of an input Thanks #Tim Down
this.href against an <a> element to get its href
this.hostname against an <a> element to get the domain of its href
this.pathname against an <a> element to get the path of its href
this.search against an <a> element to get the querystring of its href
this.src against an element where it is valid to have a src
...I think you get the idea.
There will be times when performance is crucial. Like if you're performing something in a loop many times over, you may want to ditch jQuery.
In general you can replace:
$(el).attr('someName');
with:
Above was poorly worded. getAttribute is not a replacement, but it does retrieve the value of an attribute sent from the server, and its corresponding setAttribute will set it. Necessary in some cases.
The sentences below sort of covered it. See this answer for a better treatment.
el.getAttribute('someName');
...in order to access an attribute directly. Note that attributes are not the same as properties (though they mirror each other sometimes). Of course there's setAttribute too.
Say you had a situation where received a page where you need to unwrap all tags of a certain type. It is short and easy with jQuery:
$('span').unwrap(); // unwrap all span elements
But if there are many, you may want to do a little native DOM API:
var spans = document.getElementsByTagName('span');
while( spans[0] ) {
var parent = spans[0].parentNode;
while( spans[0].firstChild ) {
parent.insertBefore( spans[0].firstChild, spans[0]);
}
parent.removeChild( spans[0] );
}
This code is pretty short, it performs better than the jQuery version, and can easily be made into a reusable function in your personal library.
It may seem like I have an infinite loop with the outer while because of while(spans[0]), but because we're dealing with a "live list" it gets updated when we do the parent.removeChild(span[0]);. This is a pretty nifty feature that we miss out on when working with an Array (or Array-like object) instead.
The correct answer is that you'll always take a performance penalty when using jQuery instead of 'plain old' native JavaScript. That's because jQuery is a JavaScript Library. It is not some fancy new version of JavaScript.
The reason that jQuery is powerful is that it makes some things which are overly tedious in a cross-browser situation (AJAX is one of the best examples) and smooths over the inconsistencies between the myriad of available browsers and provides a consistent API. It also easily facilitates concepts like chaining, implied iteration, etc, to simplify working on groups of elements together.
Learning jQuery is no substitute for learning JavaScript. You should have a firm basis in the latter so that you fully appreciate what knowing the former is making easier for you.
-- Edited to encompass comments --
As the comments are quick to point out (and I agree with 100%) the statements above refer to benchmarking code. A 'native' JavaScript solution (assuming it is well written) will outperform a jQuery solution that accomplishes the same thing in nearly every case (I'd love to see an example otherwise). jQuery does speed up development time, which is a significant benefit which I do not mean to downplay. It facilitates easy to read, easy to follow code, which is more than some developers are capable of creating on their own.
In my opinion then, the answer depends on what you're attempting to achieve. If, as I presumed based on your reference to performance benefits, you're after the best possible speed out of your application, then using jQuery introduces overhead every time you call $(). If you're going for readability, consistency, cross browser compatibility, etc, then there are certainly reasons to favor jQuery over 'native' JavaScript.
There's a framework called... oh guess what? Vanilla JS. Hope you get the joke... :D It sacrifices code legibility for performance... Comparing it to jQuery bellow you can see that retrieving a DOM element by ID is almost 35X faster. :)
So if you want performance you'd better try Vanilla JS and draw your own conclusions. Maybe you won't experience JavaScript hanging the browser's GUI/locking up the UI thread during intensive code like inside a for loop.
Vanilla JS is a fast, lightweight, cross-platform framework for
building incredible, powerful JavaScript applications.
On their homepage there's some perf comparisons:
There's already an accepted answer but I believe no answer typed directly here can be comprehensive in its list of native javascript methods/attributes that has practically guaranteed cross-browser support. For that may I redirect you to quirksmode:
http://www.quirksmode.org/compatibility.html
It is perhaps the most comprehensive list of what works and what doesn't work on what browser anywhere. Pay particular attention to the DOM section. It is a lot to read but the point is not to read it all but to use it as a reference.
When I started seriously writing web apps I printed out all the DOM tables and hung them on the wall so that I know at a glance what is safe to use and what requires hacks. These days I just google something like quirksmode parentNode compatibility when I have doubts.
Like anything else, judgement is mostly a matter of experience. I wouldn't really recommend you to read the entire site and memorize all the issues to figure out when to use jQuery and when to use plain JS. Just be aware of the list. It's easy enough to search. With time you will develop an instinct of when plain JS is preferable.
PS: PPK (the author of the site) also has a very nice book that I do recommend reading
When:
you know that there is unflinching cross-browser support for what you are doing, and
it is not significantly more code to type, and
it is not significantly less readable, and
you are reasonably confident that jQuery will not choose different implementations based on the browser to achieve better performance, then:
use JavaScript. Otherwise use jQuery (if you can).
Edit: This answer applies both when choosing to use jQuery overall versus leaving it out, as well as choosing whether to to use vanilla JS inside jQuery. Choosing between attr('id') and .id leans in favor of JS, while choosing between removeClass('foo') versus .className = .className.replace( new Regexp("(?:^|\\s+)"+foo+"(?:\\s+|$)",'g'), '' ) leans in favor of jQuery.
Others' answers have focused on the broad question of "jQuery vs. plain JS." Judging from your OP, I think you were simply wondering when it's better to use vanilla JS if you've already chosen to use jQuery. Your example is a perfect example of when you should use vanilla JS:
$(this).attr('id');
Is both slower and (in my opinion) less readable than:
this.id.
It's slower because you have to spin up a new JS object just to retrieve the attribute the jQuery way. Now, if you're going to be using $(this) to perform other operations, then by all means, store that jQuery object in a variable and operate with that. However, I've run into many situations where I just need an attribute from the element (like id or src).
Are there any other common practices
like this? Where certain Javascript
operations could be accomplished
easier, without bringing jQuery into
the mix. Or is this a rare case? (of a
jQuery "shortcut" actually requiring
more code)
I think the most common case is the one you describe in your post; people wrapping $(this) in a jQuery object unnecessarily. I see this most often with id and value (instead using $(this).val()).
Edit: Here's an article that explains why using jQuery in the attr() case is slower. Confession: stole it from the tag wiki, but I think it's worth mentioning for the question.
Edit again: Given the readability/performance implications of just accessing attributes directly, I'd say a good rule of thumb is probably to try to to use this.<attributename> when possible. There are probably some instances where this won't work because of browser inconsistencies, but it's probably better to try this first and fall back on jQuery if it doesn't work.
If you are mostly concerned about performance, your main example hits the nail on the head. Invoking jQuery unnecessarily or redundantly is, IMHO, the second main cause of slow performance (the first being poor DOM traversal).
It's not really an example of what you're looking for, but I see this so often that it bears mentioning: One of the best ways to speed up performance of your jQuery scripts is to cache jQuery objects, and/or use chaining:
// poor
$(this).animate({'opacity':'0'}, function() { $(this).remove(); });
// excellent
var element = $(this);
element.animate({'opacity':'0'}, function() { element.remove(); });
// poor
$('.something').load('url');
$('.something').show();
// excellent
var something = $('#container').children('p.something');
something.load('url').show();
I've found there is certainly overlap between JS and JQ. The code you've shown is a good example of that. Frankly, the best reason to use JQ over JS is simply browser compatibility. I always lean toward JQ, even if I can accomplish something in JS.
This is my personal view, but as jQuery is JavaScript anyway, I think theoretically it cannot perform better than vanilla JS ever.
But practically it may perform better than hand-written JS, as one's hand-written code may be not as efficient as jQuery.
Bottom-line - for smaller stuff I tend to use vanilla JS, for JS intensive projects I like to use jQuery and not reinvent the wheel - it's also more productive.
The first answer's live properties list of this as a DOM element is quite complete.
You may find also interesting to know some others.
When this is the document :
this.forms to get an HTMLCollection of the current document forms,
this.anchors to get an HTMLCollection of all the HTMLAnchorElements with name being set,
this.links to get an HTMLCollection of all the HTMLAnchorElements with href being set,
this.images to get an HTMLCollection of all the HTMLImageElements
and the same with the deprecated applets as this.applets
When you work with document.forms, document.forms[formNameOrId] gets the so named or identified form.
When this is a form :
this[inputNameOrId] to get the so named or identified field
When this is form field:
this.type to get the field type
When learning jQuery selectors, we often skip learning already existing HTML elements properties, which are so fast to access.
As usual I'm coming late to this party.
It wasn't the extra functionality that made me decide to use jQuery, as attractive as that was. After all nothing stops you from writing your own functions.
It was the fact that there were so many tricks to learn when modifying the DOM to avoid memory leaks (I'm talking about you IE). To have one central resource that managed all those sort of issues for me, written by people who were a whole lot better JS coders than I ever will be, that was being continually reviewed, revised and tested was god send.
I guess this sort of falls under the cross browser support/abstraction argument.
And of course jQuery does not preclude the use of straight JS when you needed it. I always felt the two seemed to work seamlessly together.
Of course if your browser is not supported by jQuery or you are supporting a low end environment (older phone?) then a large .js file might be a problem. Remember when jQuery used to be tiny?
But normally the performance difference is not an issue of concern. It only has to be fast enough. With Gigahertz of CPU cycles going to waste every second, I'm more concerned with the performance of my coders, the only development resources that doesn't double in power every 18 months.
That said I'm currently looking into accessibility issues and apparently .innerHTML is a bit of a no no with that. jQuery of course depends on .innerHTML, so now I'm looking for a framework that will depend on the somewhat tedious methods that are allowed. And I can imagine such a framework will run slower than jQuery, but as long as it performs well enough, I'll be happy.
Here's a non-technical answer - many jobs may not allow certain libraries, such as jQuery.
In fact, In fact, Google doesn't allow jQuery in any of their code (nor React, because it's owned by Facebook), which you might not have known until the interviewer says "Sorry, but you cant use jQuery, it's not on the approved list at XYZ Corporation". Vanilla JavaScript works absolutely everywhere, every time, and will never give you this problem. If you rely on a library yes you get speed and ease, but you lose universality.
Also, speaking of interviewing, the other downside is that if you say you need to use a library to solve a JavaScript problem during a code quiz, it comes across like you don't actually understand the problem, which looks kinda bad. Whereas if you solve it in raw vanilla JavaScript it demonstrates that you actually understand and can solve every part of whatever problem they throw in front of you.
$(this) is different to this :
By using $(this) you are ensuring the jQuery prototype is being passed onto the object.

Is IxEdit worth?

I am intrigued by IxEdit and its full-javascript approach that should allow to build nice web pages powered by JQuery effects.
I like also the opportunity to use it on many platforms.
But, is it worth a try ?
Is it complete ? Has it compatibility issues ? Are there better alternative tools ?
Don't rely on WYSIWYG editors--My guess is that this editor screws up performance like Frontpage, Dreamweaver -and the likes screws up HTML.
jQuery is pretty simple to understand, once you get hold of the concept of anonymous functions.. And with Stack Overflow at hand, you should be able to get where you want to go in no time.
Also: jQuery is the framework with the largest community and the framework with the largest plugin repository--need a gallery-thingie? No biggie, just browse the tons of plugins and find one that fits your needs.
Well, as JQuery isn't THAT complicated, I wouldn't pay for tools like that.
They also don't support any plugins I guess.
But it's free, so just try it...
I've just d/l IxEdit and am actually kind of excited about it.
It seems you do have to be careful about starting with a blank slate: I tried applying it to an existing page with a few jQ plugins and and it broke.
As for the WYSIWYG aspect of it, I think it would be great for beginners, as it generates the code on the fly, and you have to copy and paste the code into the page. This can give a noob the opportunity to see the code that's made and make sense of how it works.
My two cents.

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