The length() Property is used to return the collection of all HTML elements in a document. It is read-only property and is quite useful when a user wants to loop through an HTML Collection.
Syntax:
HTMLCollection.length
Return Value: It returns a number which represent the number of all elements in a HTML Collection.
Below example shows how to count the all <p> element in the html collection:
Example-1:
HTML
<!DOCTYPE html>
< html >
< head >
< style >
h1 {
color: green;
}
</ style >
</ head >
< body >
< center >
< h1 >GeeksForGeeks</ h1 >
< h2 >
HTMLCollection length Property
</ h2 >
< p >
The length property is used to return the
number of all elements in a HTMLCollection.
</ p >
< div >
< p >GeeksForGeeks</ p >
< p >A Computer science portal for geeks</ p >
</ div >
< button onclick = "Geeks()" >Submit</ button >
< script >
function Geeks() {
var l =
document.getElementsByTagName("P").length;
alert(l);
}
</ script >
</ center >
</ body >
</ html >
|
Output:
Before clicking on the button:

After clicking on the button:

Example-2: To highlight all the elements with class GFG using length property.
HTML
<!DOCTYPE html>
< html >
< head >
< style >
h1 {
color: green;
}
</ style >
</ head >
< body >
< center >
< h1 >GeeksForGeeks</ h1 >
< h2 >HTMLCollection length Property</ h2 >
< p >
The length property is used to return the
number of all elements in a HTMLCollection.
</ p >
< div >
< p class = "GFG" >GeeksForGeeks</ p >
< p class = "GFG" >
A Computer science portal for geeks
</ p >
</ div >
< button onclick = "Geeks()" >Submit</ button >
< script >
function Geeks() {
var w, c;
w = document.getElementsByClassName("GFG");
for (c = 0; c < w.length ; c++) {
w[c] .style.backgroundColor = "BLUE" ;
}
}
</script>
</ center >
</ body >
</ html >
|
Output:
Before clicking on the button:

After clicking on the button:

Supported Browsers: The browser supported by HTMLCollection length property are listed below:
- Google Chrome 1
- Edge 12
- Internet Explorer 8
- Firefox 1
- Opera 12.1
- Safari 1
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Last Updated :
10 Aug, 2022
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