The HTML DOM Form length property is used for returning the number of elements that are present inside the form. It is a read-only property.
Syntax
Following is the syntax of the Form length property −
ormObject.length
Example
Let us look at an example of the Form length property −
<!DOCTYPE html>
<html>
<head>
<style>
form{
border:2px solid blue;
margin:2px;
padding:4px;
}
</style>
<script>
function getLength() {
var len=document.getElementById("FORM1").length ;
document.getElementById("Sample").innerHTML = "Number of elements present inside the form are :"+len;
}
</script>
</head>
<body>
<h1>Form length property example</h1>
<form id="FORM1">
<label>User Name <input type="text" name="usrN"></label> <br>lt;br>
<label>Password <input type="password" name="pass"></label> <br><br>
<select name="Fruit">
<option value="Mango">Mango<option>
<option value="Litchi">Litchi</option>
<option value="Guava">Guava</option>
</select>
</form>
<br>
<p>Get the number of elements present in the above form by clicking the below button</p>
<button onclick="getLength()">get Length</button>
<p id="Sample"></p>
</body>
</html>Output
This will produce the following output −
On clicking the “get Length” button −
In the above example −
We have first created a form with id=“FORM1” and it contains a input field with type text, another one with type “password”. It also contains a <select> element for making a drop down list. It means the total elements inside the form element are three −
<form id="FORM1"> <label>User Name <input type="text" name="usrN"></label> <br><br> <label>Password <input type="password" name="pass"></label> <br><br> <select name="Fruit"> <option value="Mango">Mango<option> <option value="Litchi">Litchi</option> <option value="Guava">Guava</option> </select> </form>
We then created a button “get Length” that will execute the getLength() method when clicked by the user −
function getLength() {
var len=document.getElementById("FORM1").length ;
document.getElementById("Sample").innerHTML = "Number of elements present inside the form are :"+len;
}The getLength() function gets the <form> element using the getElementById() method of the document object and assigns its length property value to variable len. Since there are 3 elements inside the form element, it returns 3. This value is then displayed in the paragraph with id “Sample” using its innerHTML property and assigning text to it.
function getLength() {
var len=document.getElementById("FORM1").length ;
document.getElementById("Sample").innerHTML = "Number of elements present inside the form are :"+len;
}