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
varx = document.getElementsByTagName("p");
The elements in the collection can be accessed by an index number.To access the second <p> element you can write:
y = x[1];
HTML HTMLCollection Length
The length property defines the number of elements in an HTMLCollection:Example
var myCollection = document.getElementsByTagName("p");
document.getElementById("demo").innerHTML = myCollection.length;
- Create a collection of all <p> elements
- Display the length of the collection
Example
Change the background color of all <p> elements:var myCollection = document.getElementsByTagName("p");
var i;
for (i = 0; i < myCollection.length; i++) {
myCollection[i].style.backgroundColor = "red";
}
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.
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.