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JavaScript HTML DOM Collections


The HTMLCollection Object
The getElementsByTagName() method returns an HTMLCollection object.
An HTMLCollection object is
an array-like list (collection) of HTML elements.
The following code selects all <p> elements in a document:

Example

const myCollection = document.getElementsByTagName("p");

The elements in the collection can be accessed by an index number.
To access the
second <p> element you can write:

myCollection[1]

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Note: The index starts at 0.

HTML HTMLCollection Length
The length property defines the number of elements in an HTMLCollection:

Example

myCollection.length

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The length property is useful when you want to loop through the elements in a
collection:

Example
Change the text color of all <p> elements:

const myCollection = document.getElementsByTagName("p");
for (let i = 0; i < myCollection.length; i++) {
  myCollection.style.color = "red";
}

Try it Yourself »


An HTMLCollection is NOT an array!
An HTMLCollection may look
like an array, but it is not.
You can loop through the list and refer to
the elements with a number (just like an array).
However, you cannot use array methods like valueOf(), pop(), push(),
or join() on an HTMLCollection.













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Reference: https://www.w3schools.com/js/js_htmldom_collections.asp