What is the best way to loop through an HTMLCollection?

In my HTML, I have some elements with the class node-item. To access them in my component, I use the following code:

let nodeItems = document.getElementsByClassName('node-item');

When I log nodeItems, it shows me a HTMLCollection[] containing 4 items.

Despite trying different methods, I am unable to iterate over the nodeItems:

1. First Attempt:

let bar = [].slice.call(nodeItems);
for (var g of bar){
    console.log(g); //does not output anything
} 

2. Second Attempt:

for(let c of <any>nodeItems) {
    console.log(c); //still does not display anything
}

I have also experimented with array and object iteration, but kept getting undefined or an error. Additionally, I attempted:

let nodeItems = document.querySelector(selectors);

However, this did not resolve the issues either.

Answer №1

In the realm of coding, nodeItems embodies an essence akin to that of an HTMLCollection, best likened to an object with array-like properties.

Within the expanse of contemporary browsers, this entity is deemed iterable. It is important to note that support for iterators can be achieved by enabling the downlevelIteration compiler option. In such scenarios, a snippet of code like the one below would come into play:

const nodeItems = document.getElementsByClassName('node-item');

for (const c of nodeItems) {
  // ...
}

In cases where older browser versions are in effect, iterables can be polyfilled. The solution lies within core-js which offers polyfills for DOM iterables.

Alternately, if circumstances demand, the conversion of nodeItems into an array can be executed, paving the way for customary iteration techniques:

const nodeItems = Array.from(document.getElementsByClassName('node-item'));

for (const c of nodeItems) {
  // ...
}

Answer №2

To access elements with the class 'node-item' in an array-like format, you can simply use either

Array.from(document.getElementsByClassName('node-item'))
or the spread operator like this:
[...document.getElementsByClassName('node-item')]
. Once you have this array-like structure, you can utilize array methods on it just like you would with a regular array.

If you prefer a more traditional approach, you can also iterate through the elements using a standard for loop like below:

let nodeItems = document.getElementsByClassName('node-item');
for (let i = 0; i < nodeItems.length; i++) {
    // access current element using nodeItems[i]
}

Answer №3

An effective way to create an array from elements selected with spread operator is by using document.querySelectorAll.

Take a look at this code snippet:

let nodeItems = [...(document.querySelectorAll('.class1'))];

for (var g of nodeItems) {
  console.log( g.innerHTML ); 
}
<div class='class1'>Text 1</div>
<div class='class1'>Text 2</div>
<div class='class1'>Text 3</div>

More information: Spread Syntax

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