In this article I will explain with an example, how to implement OnClick event of HTML RadioButton using JavaScript.
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.
RadioButton OnClick event example in JavaScript
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"); = chkYes.checked ? "block" : "none";
<span>Do you have Passport?</span>
<label for="chkYes">
    <input type="radio" id="chkYes" name="chkPassPort" onclick="ShowHideDiv()" />
<label for="chkNo">
    <input type="radio" id="chkNo" name="chkPassPort" onclick="ShowHideDiv()" />
<hr />
<div id="dvPassport" style="display: none">
    Passport Number:
    <input type="text" id="txtPassportNumber" />
RadioButton OnClick event example in JavaScript
Browser Compatibility

The above code has been tested in the following browsers.

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