In this article I will explain with an example, how to call JavaScript function when an HTML RadioButton is checked (selected) or unchecked (unselected).
For illustration purposes, when the RadioButton is clicked based on whether it is checked (selected) or unchecked (unselected), a JavaScript function will be called within which the HTML DIV with TextBox will be shown or hidden.
 
 
Call JavaScript function when RadioButton is checked or unchecked in HTML
The HTML Markup consists of two RadioButtons (one for Yes and other for No) and an HTML DIV consisting of a TextBox. Each RadioButton has been assigned a JavaScript OnClick event handler.
Note: The RadioButtons must be set with exact same name attribute values in order to make them mutually exclusive.
When the RadioButton is clicked, the ShowHideDiv JavaScript function is executed. Inside this function, based on whether Yes RadioButton is checked (selected) or unchecked (unselected), the HTML DIV with TextBox is shown or hidden.
<script type="text/javascript">
    function ShowHideDiv() {
        var chkYes = document.getElementById("chkYes");
        var dvPassport = document.getElementById("dvPassport");
        dvPassport.style.display = chkYes.checked ? "block" : "none";
    }
</script>
<span>Do you have Passport?</span>
<label for="chkYes">
    <input type="radio" id="chkYes" name="chkPassPort" onclick="ShowHideDiv()" />
    Yes
</label>
<label for="chkNo">
    <input type="radio" id="chkNo" name="chkPassPort" onclick="ShowHideDiv()" />
    No
</label>
<hr />
<div id="dvPassport" style="display: none">
    Passport Number:
    <input type="text" id="txtPassportNumber" />
</div>
 
 
Screenshot
Call JavaScript function when RadioButton is checked or unchecked in HTML
 
 
Browser Compatibility

The above code has been tested in the following browsers.

Internet Explorer  FireFox  Chrome  Safari  Opera 

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Demo
 
 
Downloads
Show_Hide_DIV_RadioButton.zip