Lesson 20: The Checkbox

In this lesson, we shall learn how to write code for the JavaScript checkbox. Checkboxes are differently from radio buttons. While radio buttons only allow the user to select one option at a time, checkboxes allow the users to select multiple options. You can try to click on the radio buttons and the checkboxes below:

The status of a checkbox is either check or unchecked. A checkbox can be created in a web page using the following syntax:

<input type="checkbox" name="Checkbox1" value="chkbox1">Item1

20.1 Using the checkboxes

In this example, the user can verify whether a checkbox is checked or not.

Example 20.1: Code for Item Selection

<script>
function checkstatus()
{ if(MyForm.Checkbox1.checked)
document.write(MyForm.Checkbox1.value+" is selected");
else
document.write(MyForm.Checkbox1.value+" is not selected");

}
</script>

Also create a checkbox as follows:

<form>
<input value="Click" onclick="checkstatus()">
<input Value="Item1">Item1
</form>

Try out the JavaScript by clicking the button below:

You can modify the above program by adding more than one checkboxes to the page. The code is able to show the user how many checkboxes are being selected.

Example 20.2: To Check Status of Multiple Checkboxes

<script>
function checkstatus1()
{for(count=0;count<4;count++)
{if (MyForm.MyCheckbox[count].checked)
alert(MyForm.MyCheckbox[count].value+" is selected");
}

}

</script>

<form name="MyForm2">
<input type="button" value="Click" onclick="checkstatus1()"><br>
<input type="checkbox" Value="Item1">Item1<br>
<input type="checkbox" Value="Item2">Item2<br>
<input type="checkbox"Value="Item3">Item3<br>
<input type="checkbox"Value="Item4">Item4<br>
</form>
</body>

</html>