Best way to get child nodes

Question

I was wondering  JavaScript offers a variety of methods to get the first child element from any element  but which is the best  By best  I mean  most cross-browser compatible  fastest  most comprehensive and predictable when it comes to behaviour  A list of methods properties I use as aliases   var elem   document getElementById  container    var child   elem children 0   var child   elem firstElementChild        children 0    This works for both cases   var child   elem childNodes 0      or childNodes 1   see below   That   s in case of forms  or  lt div gt  iteration  If I might encounter text elements   var child   elem childNodes     treat as NodeList var child   elem firstChild    As far as I can work out  firstChild uses the NodeList from childNodes  and firstElementChild uses children  I   m basing this assumption on the MDN reference      childNode is a reference to the first child element of the element node  or null if there isn   t one    I   m guessing that  in terms of speed  the difference  if any  will be next to nothing  since firstElementChild is effectively a reference to children 0   and the children object is already in memory anyway   What does throw me  is the childNodes object  I   ve used it to take a look at a form  in a table element  While children lists all form elements  childNodes also seems to include whitespace from the HTML code   console log elem childNodes 0    console log elem firstChild     Both log  lt TextNode textContent   n   gt   console log elem childNodes 1    console log elem children 0    console log elem firstElementChild     All log  lt input type  text     gt   How come  I   d understand that one object would allow me to work with the    raw    HTML code  while the other sticks to the DOM  but the childNodes element seems to work on both levels   To get back to my initial question  my guess would be  if I want the most comprehensive object  childNodes is the way to go  but because of its comprehensiveness  it might not be the most predictable in terms of it returning the element I want expect at any given moment  Cross-browser support might also prove to be a challenge in that case  though I could be wrong   Could anyone clarify the distinction between the objects at hand  If there is a speed difference  however negligible  I   d like to know  too  If I   m seeing this all wrong  feel free to educate me     PS  Please  please  I like JavaScript  so yes  I want to deal with this sort of thing  Answers like    jQuery deals with this for you    are not what I   m looking for  hence no jquery tag

User · Accepted Answer

Sounds like you re overthinking it  You ve observed the difference between childNodes and children  which is that childNodes contains all nodes  including text nodes consisting entirely of whitespace  while children is a collection of just the child nodes that are elements  That s really all there is to it   There is nothing unpredictable about either collection  although there are a couple of issues to be aware of    IE  lt   8 do not include white space-only text nodes in childNodes while other browsers do IE  lt   8 includes comment nodes within children while other browsers only have elements   children  firstElementChild and friends are just conveniences  presenting a filtered view of the DOM restricted to just elements

User · Answer

The cross browser way to do is to use childNodes to get NodeList  then make an array of all nodes with nodeType ELEMENT NODE          Return direct children elements         param  HTMLElement      return  Array      function elementChildren  element        var childNodes   element childNodes          children               i   childNodes length       while  i--            if  childNodes i  nodeType    1                children unshift childNodes i                         return children      http   jsfiddle net s4kxnahu   This is especially easy if you are using a utility library such as lodash          Return direct children elements         param  HTMLElement      return  Array      function elementChildren  element        return   where element childNodes   nodeType  1        Future   You can use querySelectorAll in combination with  scope pseudo-class  matches the element that is the reference point of the selector    parentElement querySelectorAll   scope  gt         At the time of writing this  scope is supported in Chrome  Firefox and Safari

User · Answer

firstElementChild might not be available in IE lt 9  only firstChild   on IE lt 9 firstChild is the firstElementChild because MS DOM  IE lt 9  is not storing empty text nodes  But if you do so on other browsers they will return empty text nodes     my solution   child  elem firstElementChild  elem firstChild    this will give the firstchild even on IE lt 9

User · Answer

Just to add to the other answers  there are still noteworthy differences here  specifically when dealing with  lt svg gt  elements   I have used both  childNodes and  children and have preferred working with the HTMLCollection delivered by the  children getter   Today however  I ran into issues with IE Edge failing when using  children on an  lt svg gt   While  children is supported in IE on basic HTML elements  it isn t supported on document document fragments  or SVG elements    For me  I was able to simply grab the needed elements via  childNodes n  because I don t have extraneous text nodes to worry about  You may be able to do the same  but as mentioned elsewhere above  don t forget that you may run into unexpected elements   Hope this is helpful to someone scratching their head trying to figure out why  children works elsewhere in their js on modern IE and fails on document or SVG elements

User · Answer

Don t let white space fool you  Just test this in a console browser  Use native javascript  Here is and example with two  ul  sets with the same class  You don t need to have your  ul  list all in one line to avoid white space just use your array count to jump over white space  How to get around white space with querySelector   then childNodes   js fiddle link  https   jsfiddle net aparadise 56njekdo  var y   document querySelector   list    var myNode   y childNodes 11  style backgroundColor  red     lt ul class  quot list quot  gt       lt li gt 8 lt  li gt       lt li gt 9 lt  li gt       lt li gt 100 lt  li gt   lt  ul gt    lt ul class  quot list quot  gt       lt li gt ABC lt  li gt       lt li gt DEF lt  li gt       lt li gt XYZ lt  li gt   lt  ul gt

[javascript] Best way to get child nodes

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