Loop through childNodes

Question

I m trying to loop through childNodes like this   var children   element childNodes  children forEach function item       console log item         However  it output Uncaught TypeError  undefined is not a function due to forEach function  I also try to use children instead of childNodes but nothing changed   Does anybody know what s going on

User · Answer

I m very late to the party  but since element lastChild nextSibling     null  the following seems like the most straightforward option to me   for var child element firstChild  child   null  child child nextSibling        console log child

User · Answer

Try with for loop  It gives error in forEach because it is a collection of nodes nodelist   Or this should convert node-list to array   function toArray obj      var array         for  var i   0  i  lt  obj length  i           array i    obj i       return array      Or you can use this   var array   Array prototype slice call obj

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If you do a lot of this sort of thing then it might be worth defining the function for yourself   if  typeof NodeList prototype forEach     undefined        NodeList prototype forEach   function  cb           for  var i 0  i  lt  this length  i                  var node   this i               cb  node  i

User · Answer

Try this  reverse order traversal    var childs   document getElementById  parent   childNodes  var len   childs length  if len --  do       console log  node     childs len      while len --     OR  in order traversal   var childs   document getElementById  parent   childNodes  var len   childs length  i   -1  if   i  lt  len  do       console log  node     childs i      while   i  lt  len

User · Answer

Here is how you can do it with for-in loop   var children   element childNodes   for child in children       console log children child

User · Answer

Couldn t resist to add another method  using childElementCount  It returns the number of child element nodes from a given parent  so you can loop over it   for var i 0  len   parent childElementCount   i  lt  len    i           do something with parent children i

User · Answer

const results   Array from myNodeList values    map parser item     NodeList is not Array but NodeList values   return a Array Iterator  so can convert it to Array

User · Answer

The variable children is a NodeList instance and NodeLists are not true Array and therefore they do not inherit the forEach method   Also some browsers actually support it nodeList forEach    ES5  You can use slice from Array to convert the NodeList into a proper Array   var array   Array prototype slice call children    You could also simply use call to invoke forEach and pass it the NodeList as context      forEach call children  function child          ES6  You can use the from method to convert your NodeList into an Array   var array   Array from children    Or you can also use the spread syntax     like so  let array        children       A hack that can be used is NodeList prototype forEach   Array prototype forEach and you can then use forEach with any NodeList without having to convert them each time   NodeList prototype forEach   Array prototype forEach var children   element childNodes  children forEach function item       console log item           See A comprehensive dive into NodeLists  Arrays  converting NodeLists and understanding the DOM for a good explanation and other ways to do it

User · Answer

Here is a functional ES6 way of iterating over a NodeList  This method uses the Array s forEach like so   Array prototype forEach call element childNodes  f    Where f is the iterator function that receives a child nodes as it s first parameter and the index as the second   If you need to iterate over NodeLists more than once you could create a small functional utility method out of this   const forEach   f   gt  x   gt  Array prototype forEach call x  f       For example  to log all child nodes forEach  item    gt    console log item      element childNodes      The functional forEach is handy as you can easily created curried functions const logChildren   forEach  childNode    gt    console log childNode      logChildren elementA childNodes  logChildren elementB childNodes     You can do the same trick for map   and other Array functions

[javascript] Loop through childNodes

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