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");
Note: The index starts at 0.
HTML HTMLCollection Length
The length property defines the number of elements in an HTMLCollection:
Example
myCollection.length
The length property is useful when you want to loop through the elements in a collection:
Example
const myCollection = document.getElementsByTagName("p");
for (let i = 0; i < myCollection.length; i++) {
myCollection[i].style.color = "red";
}
Note: 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.