document getElementById vs jQuery

Question

Is this   var contents   document getElementById  contents      The same as this   var contents       contents      Given that jQuery is loaded

User · Answer

One other difference  getElementById returns the first match  while           returns a collection of matches - yes  the same ID can be repeated in an HTML doc    Further  getElementId is called from the document  while           can be called from a selector  So  in the code below  document getElementById  content   will return the entire body but    form  content   0  will return inside of the form    lt body id  content  gt      lt h1 gt Header  lt  h1 gt      lt form gt         lt div id  content  gt  My Form  lt  div gt      lt  form gt   lt  body gt    It might seem odd to use duplicate IDs  but if you are using something like Wordpress  a template or plugin might use the same id as you use in the content  The selectivity of jQuery could help you out there

User · Answer

No   Calling document getElementById  id   will return a raw DOM object   Calling     id   will return a jQuery object that wraps the DOM object and provides jQuery methods   Thus  you can only call jQuery methods like css   or animate   on the     call   You can also write   document getElementById  id     which will return a jQuery object and is equivalent to     id     You can get the underlying DOM object from a jQuery object by writing     id   0

User · Answer

Just like most people have said  the main difference is the fact that it is wrapped in a jQuery object with the jQuery call vs the raw DOM object using straight JavaScript  The jQuery object will be able to do other jQuery functions with it of course but  if you just need to do simple DOM manipulation like basic styling or basic event handling  the straight JavaScript method is always a tad bit faster than jQuery since you don t have to load in an external library of code built on JavaScript  It saves an extra step

User · Answer

A note on the difference in speed   Attach the following snipet to an onclick call  function myfunc         var timer   new Date                 for var i   0  i  lt  10000  i                            document getElementById  myID                    myID   0                       console log  timer       new Date   - timer       Alternate commenting one out and then comment the other out   In my tests   document getElementbyId averaged about 35ms  fluctuating from 25ms up to 52ms on about 15 runs   On the other hand  the  jQuery averaged about 200ms  ranging from 181ms to 222ms on about 15 runs   From this simple test you can see that the jQuery took about 6 times as long   Of course  that is over 10000 iterations so in a simpler situation I would probably use the jQuery for ease of use and all of the other cool things like  animate and  fadeTo   But yes  technically getElementById is quite a bit faster

User · Answer

Not exactly    document getElementById  contents      returns a HTML DOM Object  var contents       contents       returns a jQuery Object     In jQuery  to get the same result as document getElementById  you can access the jQuery Object and get the first element in the object  Remember JavaScript objects act similar to associative arrays    var contents       contents   0     returns a HTML DOM Object

User · Answer

jQuery is built over JavaScript  This means that it s just javascript anyway   document getElementById       The document getElementById   method returns the element that has the ID attribute with the specified value and Returns null if no elements with the specified ID exists An ID should be unique within a page    Jquery         Calling jQuery   or     with an id selector as its argument will return a jQuery object containing a collection of either zero or one DOM element Each id value must be used only once within a document  If more than one element has been assigned the same ID  queries that use that ID will only select the first matched element in the DOM

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All the answers are old today as of 2019 you can directly access id keyed filds in javascript simply try it    lt p id  mytext  gt  lt  p gt   lt script gt mytext innerText    Yes that works   lt  script gt    Online Demo  - https   codepen io frank-dspeed pen mdywbre

User · Answer

All the answers above are correct  In case you want to see it in action  don t forget you have Console in a browser where you can see the actual result crystal clear    I have an HTML     lt div id  contents  gt  lt  div gt    Go to console  cntrl shift c  and use these commands to see your result clearly  document getElementById  contents    gt  gt  gt  div contents      contents    gt  gt  gt   div contents   context  document   selector    contents    jquery   1 10 1    constructor  function   init  function        As we can see  in the first case we got the tag itself  that is  strictly speaking  an HTMLDivElement object   In the latter we actually don   t have a plain object  but an array of objects  And as mentioned by other answers above  you can use the following command       contents   0   gt  gt  gt  div contents

User · Answer

No  actually the same result would be       contents   0     jQuery does not know how many results would be returned from the query   What you get back is a special jQuery object which is a collection of all the controls that matched the query   Part of what makes jQuery so convenient is that MOST methods called on this object that look like they are meant for one control  are actually in a loop called on all the members int he collection  When you use the  0  syntax you take the first element from the inner collection   At this point you get a DOM object

User · Answer

var contents   document getElementById  contents     var contents       contents     The code snippets are not the same  first one returns a Element object  source   The second one  jQuery equivalent will return a jQuery object containing a collection of either zero or one DOM element   jQuery documentation   Internally jQuery uses document getElementById   for efficiency    In both the cases if more than one element found only the first element will be returned     When checking the github project for jQuery I found following line snippets which seems to be using document getElementById codes  https   github com jquery jquery blob master src core init js line 68 onwards       HANDLE     id    else       elem   document getElementById  match 2

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I developed a noSQL database for storing DOM trees in Web Browsers where references to all DOM elements on page are stored in a short index  Thus function  getElementById    is not needed to get modify an element  When elements in DOM tree are instantiated on page the database assigns surrogate primary keys to each element  It is a free tool http   js2dx com

User · Answer

In case someone else hits this    Here s another difference   If the id contains characters that are not supported by the HTML standard  see SO question here  then jQuery may not find it even if getElementById does   This happened to me with an id containing     characters  ex  id  a b c    using Chrome    var contents   document getElementById  a b c      was able to find my element but    var contents       a b c      did not   Btw  the simple fix was to move that id to the name field  JQuery had no trouble finding the element using   var contents       myclass name  a b c

User · Answer

Close  but not the same  They re getting the same element  but the jQuery version is wrapped in a jQuery object   The equivalent would be this  var contents       contents   get 0     or this  var contents       contents   0     These will pull the element out of the jQuery object

User · Answer

No  The first returns a DOM element  or null  whereas the second always returns a jQuery object  The jQuery object will be empty if no element with the id of contents was matched   The DOM element returned by document getElementById  contents   allows you to do things such as change the  innerHTML  or  value  etc  however you ll need to use jQuery methods on the jQuery Object   var contents       contents   get 0     Is more equivilent  however if no element with the id of contents is matched  document getElementById  contents   will return null  but     contents   get 0  will return undefined   One benefit on using the jQuery object is that you won t get any errors if no elements were returned  as an object is always returned  However you will get errors if you try to perform operations on the null returned by document getElementById

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