jQuery vs document querySelectorAll

Question

I heard several times that jQuery s strongest asset is the way it queries and manipulates elements in the DOM  you can use CSS queries to create complex queries that would be very hard to do in regular javascript    However   as far as I know  you can achieve the same result with document querySelector or document querySelectorAll  which are supported in Internet Explorer 8 and above    So the question is this  why  risk  jQuery s overhead if its strongest asset can be achieved with pure JavaScript    I know jQuery has more than just CSS selectors  for example cross browser AJAX  nice event attaching etc  But its querying part is a very big part of the strength of jQuery   Any thoughts

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That s because jQuery can do much more than querySelectorAll   First of all  jQuery  and Sizzle  in particular   works for older browsers like IE7-8 that doesn t support CSS2 1-3 selectors   Plus  Sizzle  which is the selector engine behind jQuery  offers you a lot of more advanced selector instruments  like the  selected pseudo-class  an advanced  not   selector  a more complex syntax like in     gt   children   and so on   And it does it cross-browsers  flawlessly  offering all that jQuery can offer  plugins and APIs    Yes  if you think you can rely on simple class and id selectors  jQuery is too much for you  and you d be paying an exaggerated pay-off  But if you don t  and want to take advantage of all jQuery goodness  then use it

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document querySelectorAll   has several inconsistencies across browsers and is not supported in older browsersThis probably won t cause any trouble anymore nowadays  It has a very unintuitive scoping mechanism and some other not so nice features  Also with javascript you have a harder time working with the result sets of these queries  which in many cases you might want to do  jQuery provides functions to work on them like  filter    find    children    parent    map    not   and several more  Not to mention the jQuery ability to work with pseudo-class selectors   However  I would not consider these things as jQuery s strongest features but other things like  working  on the dom  events  styling  animation  amp  manipulation  in a crossbrowser compatible way or the ajax interface   If you only want the selector engine from jQuery you can use the one jQuery itself is using  Sizzle That way you have the power of jQuerys Selector engine without the nasty overhead   EDIT  Just for the record  I m a huge vanilla JavaScript fan  Nonetheless it s a fact that you sometimes need 10 lines of JavaScript where you would write 1 line jQuery   Of course you have to be disciplined to not write jQuery like this      ul first   find   foo   css  background-color    red   end   find   bar   css  background-color    green   end      This is extremely hard to read  while the latter is pretty clear      ul first       find   foo          css  background-color    red    end       find   bar          css  background-color    green    end      The equivalent JavaScript would be far more complex illustrated by the pseudocode above   1  Find the element  consider taking all element or only the first         ul first      taking querySelectorAll has to be considered var e   document querySelector  ul first      2  Iterate over the array of child nodes via some  possibly nested or recursive  loops and check the class  classlist not available in all browsers       find   foo   for  var i   0 i lt e length i             older browser don t have element classList - gt  even more complex      e i  children classList contains  foo            do some more magic stuff here     3  apply the css style      css  background-color    green      note different notation element style backgroundColor    green     or element style  background-color      green    This code would be at least two times as much lines of code you write with jQuery  Also you would have to consider cross-browser issues which will compromise the severe speed advantage  besides from the reliability  of the native code

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Here s a comparison if I want to apply the same attribute  e g  hide all elements of class  my-class    This is one reason to use jQuery   jQuery       my-class   hide      JavaScript   var cls   document querySelectorAll   my-class    for  var i   0  i  lt  cls length  i          cls i  style display    none       With jQuery already so popular  they should have made document querySelector   behave just like       Instead  document querySelector   only selects the first matching element which makes it only halfway useful

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as the official site says   jQuery  The Write Less  Do More  JavaScript Library   try to translate the following jQuery code without any library     p neat   addClass  ohmy   show  slow

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I think the true answer is that jQuery was developed long before querySelector querySelectorAll became available in all major browsers   Initial release of jQuery was in 2006  In fact  even jQuery was not the first which implemented CSS selectors   IE was the last browser to implement querySelector querySelectorAll  Its 8th version was released in 2009   So now  DOM elements selectors is not the strongest point of jQuery anymore  However  it still has a lot of goodies up its sleeve  like shortcuts to change element s css and html content  animations  events binding  ajax

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Just a comment on this  when using material design lite  jquery selector does not return the property for material design for some reason   For    lt div class  logonfield mdl-textfield mdl-js-textfield mdl-textfield--floating-label  gt           lt input class  mdl-textfield  input  type  text  id  myinputfield  required gt           lt label class  mdl-textfield  label  for  myinputfield  gt Enter something   lt  label gt         lt  div gt    This works   document querySelector   myinputfield   parentNode MaterialTextfield change      This does not       myinputfield   parentNode MaterialTextfield change

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id   vs document querySelectorAll   id    The deal is with the     function it makes an array and then breaks it up for you but with document querySelectorAll   it makes an array and you have to break it up

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jQuery s Sizzle selector engine can use querySelectorAll if it s available  It also smooths out inconsistencies between browsers to achieve uniform results  If you don t want to use all of jQuery  you could just use Sizzle separately  This is a pretty fundamental wheel to invent   Here s some cherry-pickings from the source that show the kind of things jQuery w  Sizzle  sorts out for you   Safari quirks mode   if   document querySelectorAll        function        var oldSizzle   Sizzle        div   document createElement  div          id      sizzle          div innerHTML     lt p class  TEST  gt  lt  p gt            Safari can t handle uppercase or unicode characters when        in quirks mode      if   div querySelectorAll  amp  amp  div querySelectorAll   TEST   length     0           return          If that guard fails it uses it s a version of Sizzle that isn t enhanced with querySelectorAll  Further down there are specific handles for inconsistencies in IE  Opera  and the Blackberry browser        Check parentNode to catch when Blackberry 4 6 returns      nodes that are no longer in the document  6963   if   elem  amp  amp  elem parentNode            Handle the case where IE and Opera return items        by name instead of ID     if   elem id     match 3            return makeArray    elem    extra               else       return makeArray      extra          And if all else fails it will return the result of oldSizzle query  context  extra  seed

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To understand why jQuery is so popular  it s important to understand where we re coming from   About a decade ago  top browsers were IE6  Netscape 8 and Firefox 1 5  Back in those days  there were little cross-browser ways to select an element from the DOM besides Document getElementById     So  when jQuery was released back in 2006  it was pretty revolutionary  Back then  jQuery set the standard for how to easily select   change HTML elements and trigger events  because its flexibility and browser support were unprecedented   Now  more than a decade later  a lot of features that made jQuery so popular have become included in the javaScript standard    Instead of jQuery s      you can now now use Document querySelectorAll   Instead of jQuery s  el on    you can now use EventTarget addEventListener   Instead of jQuery s  el toggleClass    you can now use Element classList toggle         These weren t generally available back in 2005  The fact that they are today obviously begs the question of why we should use jQuery at all  And indeed  people are increasingly wondering whether we should use jQuery at all   So  if you think you understand JavaScript well enough to do without jQuery  please do  Don t feel forced to use jQuery  just because so many others are doing it

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Old question  but half a decade later  it   s worth revisiting  Here I am only discussing the selector aspect of jQuery   document querySelector All  is supported by all current browsers  down to IE8  so compatibility is no longer an issue  I have also found no performance issues to speak of  it was supposed to be slower than document getElementById  but my own testing suggests that it   s slightly faster    Therefore when it comes to manipulating an element directly  it is to be preferred over jQuery   For example   var element document querySelector  h1    element innerHTML  Hello     is vastly superior to   var  element    h1     element html  hello      In order to do anything at all  jQuery has to run through a hundred lines of code  I once traced through code such as the above to see what jQuery was actually doing with it   This is clearly a waste of everyone   s time   The other significant cost of jQuery is the fact that it wraps everything inside a new jQuery object  This overhead is particularly wasteful if you need to unwrap the object again or to use one of the object methods to deal with properties which are already exposed on the original element   Where jQuery has an advantage  however  is in how it handles collections  If the requirement is to set properties of multiple elements  jQuery has a built-in each method which allows something like this   var  elements    h2         multiple elements  elements html  hello      To do so with Vanilla JavaScript would require something like this   var elements document querySelectorAll  h2    elements forEach function e        e innerHTML  Hello         which some find daunting   jQuery selectors are also slightly different  but modern browsers  excluding IE8  won   t get much benefit   As a rule  I caution against using jQuery for new projects    jQuery is an external library adding to the overhead of the project  and to your dependency on third parties  jQuery function is very expensive  processing-wise  jQuery imposes a methodology which needs to be learned and may compete with other aspects of your code  jQuery is slow to expose new features in JavaScript    If none of the above matters  then do what you will  However  jQuery is no longer as important to cross-platform development as it used to be  as modern JavaScript and CSS go a lot further than they used to   This makes no mention of other features of jQuery  However  I think that they  too  need a closer look

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In terms of code maintainability  there are several reasons to stick with a widely used library    One of the main ones is that they are well documented  and have communities such as     say     stackexchange  where help with the libraries can be found  With a custom coded library  you have the source code  and maybe a how-to document  unless the coder s  spent more time documenting the code than writing it  which is vanishingly rare    Writing your own library might work for you   but the intern sitting at the next desk may have an easier time getting up to speed with something like jQuery   Call it network effect if you like  This isn t to say that the code will be superior in jQuery  just that the concise nature of the code makes it easier to grasp the overall structure for programmers of all skill levels  if only because there s more functional code visible at once in the file you are viewing  In this sense  5 lines of code is better than 10   To sum up  I see the main benefits of jQuery as being concise code  and ubiquity

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If you are optimizing your page for IE8 or newer  you should really consider whether you need jquery or not  Modern browsers have many assets natively which jquery provides    If you care for performance  you can have incredible performance benefits  2-10 faster  using native javascript  http   jsperf com jquery-vs-native-selector-and-element-style 2  I transformed a div-tagcloud from jquery to native javascript  IE8  compatible   the results are impressive  4 times faster with just a little overhead                       Number of lines       Execution Time                        Jquery version          340                    155ms Native version          370                    27ms   You Might Not Need Jquery provides a really nice overview  which native methods replace for which browser version   http   youmightnotneedjquery com     Appendix  Further speed comparisons how native methods compete to jquery   Array    inArray vs Array indexOf  Jquery 24  slower DOM    empty vs Node innerHtml  Jquery 97  slower DOM    on vs Node addEventListener  Jquery 90  slower DOM    find vs Node queryselectorall  Jquery 90  slower Array    grep vs Array filter  Native 70  slower DOM    show hide vs display none  Jquery 85  slower AJAX    ajax vs XMLHttpRequest  Jquery 89  slower Height    outerHeight vs offsetHeight  Jquery 87  slower Attr    attr vs setAttribute  Jquery 86  slower

[javascript] jQuery vs document.querySelectorAll

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