HTML DOM Form length Property


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;
}

Updated on: 19-Aug-2019

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