Combining Multiple NodeLists in Javascript

Question

Combining Multiple NodeLists in Javascript

Initially, I was seeking a sophisticated method to replicate the functionality of Array.concat() on the results of the getElementsByTagName function in older browsers like IE because it appeared that concat wasn't supported. However, as it turns out, the reason the returned object didn't support it is because it's not actually an Array. Whoops!

The truth is, getElementsByTagName returns a NodeList. So, the real question becomes: what's the best approach to obtain a single list containing all form elements in a document (input, select, textarea, button) for looping through them? It doesn't necessarily have to be an array... a single NodeList would also work perfectly.

Please keep in mind that I'm working with IE6 for a corporate intranet system (soon upgrading to IE8).

My solution eventually ended up being:

It turned out to be more straightforward and likely more efficient to encapsulate the code into a separate function and call it three times with the different nodelists rather than attempting to merge them together.
In the end, I switched over to using MooTools (after spending hours researching various frameworks). Now, obtaining an array of desired items is incredibly simple. I suggest utilizing a JavaScript framework like this instead of struggling to find the optimal approach yourself. Of course, I value learning the raw language (which is why I hesitated to use a framework for so long), but sometimes, the quickest way to achieve results is just as important in a business setting as improving one's proficiency with the language.

Update: Nearly two years later, I'd simply opt for jQuery and call it a day!

javascript internet-explorer concatenation nodelist

Answer 1

Answer №1

When combining nodelists, you can first convert them into arrays using Array.prototype.slice.call and then concatenate them in a regular manner.

var a = Array.prototype.slice.call(document.getElementsByTagName("p")),
    b = Array.prototype.slice.call(document.getElementsByTagName("div"))

var c = a.concat(b);

Update: (In response to your comment)

If you only have a few types of elements, this method works fine. However, as you increase the number of DOM calls, performance may decrease. It is advisable to use

document.getElementsByTagName('*')

, iterate through the list, and select the elements with the required nodeName.

Additionally, note that the Array.prototype.slice method might not be compatible with all browsers. Refer to line#723 in the comments section of sizzle.js for more information (this file is the selector engine used by jQuery).

For a simpler approach, consider using a library like jQuery which handles these complexities for you. You can achieve the same result with:

$("input, select, textarea, <other tags>")

Answer 2

When combining nodelists, you can first convert them into arrays using Array.prototype.slice.call and then concatenate them in a regular manner.

var a = Array.prototype.slice.call(document.getElementsByTagName("p")),
    b = Array.prototype.slice.call(document.getElementsByTagName("div"))

var c = a.concat(b);

Update: (In response to your comment)

If you only have a few types of elements, this method works fine. However, as you increase the number of DOM calls, performance may decrease. It is advisable to use

document.getElementsByTagName('*')

, iterate through the list, and select the elements with the required nodeName.

Additionally, note that the Array.prototype.slice method might not be compatible with all browsers. Refer to line#723 in the comments section of sizzle.js for more information (this file is the selector engine used by jQuery).

For a simpler approach, consider using a library like jQuery which handles these complexities for you. You can achieve the same result with:

$("input, select, textarea, <other tags>")

Answer 3

Answer №2

Utilizing the spread operator in ES6 opens up new possibilities.

const mergedArrays = [...array1, ...array2];

Answer 4

Utilizing the spread operator in ES6 opens up new possibilities.

const mergedArrays = [...array1, ...array2];

Answer 5

Answer №3

function combineElements(list1, list2) {
  var slice = Array.prototype.slice;
  return slice.call(list1).concat(slice.call(list2));
}

console.log( combineElements( inputs, selects ) ); // => [input, select]

Answer 6

function combineElements(list1, list2) {
  var slice = Array.prototype.slice;
  return slice.call(list1).concat(slice.call(list2));
}

console.log( combineElements( inputs, selects ) ); // => [input, select]

Answer 7

Answer №4

According to information found in the MDN Documentation, an alternative method is using Array.from to transform a NodeList into an Array for browsers that have support for it.

Answer 8

According to information found in the MDN Documentation, an alternative method is using Array.from to transform a NodeList into an Array for browsers that have support for it.

Answer 9

Answer №5

let elementsDiv=document.getElementsByTagName('div'),
elementsButton=document.getElementsByTagName('button');
elementsDiv=[].slice.call(elementsDiv, 0,elementsDiv.length).concat([].slice.call(elementsButton, 0,elementsButton.length))

Answer 10

let elementsDiv=document.getElementsByTagName('div'),
elementsButton=document.getElementsByTagName('button');
elementsDiv=[].slice.call(elementsDiv, 0,elementsDiv.length).concat([].slice.call(elementsButton, 0,elementsButton.length))

Answer 11

Answer №6

It surprises me that there are not more answers on this topic, but I decided to give it a try and came up with the following function despite having to struggle a bit.

function filterElementsByTags(element, tags) {
   var elements = element.getElementsByTagName('*');
   var filteredElements  = [];
   for (var i = 0; i < elements.length; ++i ) {
      if (tags.includes(elements[i].nodeName.toLowerCase())) {
         filteredElements.push(elements[i]);
      }
   }
   return filteredElements;
}

var formElement = document.getElementById('form');
var selectedTags = ['input', 'select'];
console.log(filterElementsByTags(formElement, selectedTags));

Answer 12

It surprises me that there are not more answers on this topic, but I decided to give it a try and came up with the following function despite having to struggle a bit.

function filterElementsByTags(element, tags) {
   var elements = element.getElementsByTagName('*');
   var filteredElements  = [];
   for (var i = 0; i < elements.length; ++i ) {
      if (tags.includes(elements[i].nodeName.toLowerCase())) {
         filteredElements.push(elements[i]);
      }
   }
   return filteredElements;
}

var formElement = document.getElementById('form');
var selectedTags = ['input', 'select'];
console.log(filterElementsByTags(formElement, selectedTags));

Combining Multiple NodeLists in Javascript

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

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