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JavaScript onkeydown Event

Definition and Usage

The onkeydown event occurs when a keyboard key is pressed.

Syntax

onkeydown="SomeJavaScriptCode"

Parameter Description
SomeJavaScriptCode Required. Specifies a JavaScript to be executed when the event occurs.

Supported by the following HTML tags:

<a>, <acronym>, <address>, <area>, <b>, <bdo>, <big>, <blockquote>, <body>, <button>, <caption>, <cite>, <code>, <dd>, <del>, <dfn>, <div>, <dt>, <em>, <fieldset>, <form>, <h1> to <h6>, <hr>, <i>, <input>, <kbd>, <label>, <legend>, <li>, <map>, <object>, <ol>, <p>, <pre>, <q>, <samp>, <select>, <small>, <span>, <strong>, <sub>, <sup>, <table>, <tbody>, <td>, <textarea>, <tfoot>, <th>, <thead>, <tr>, <tt>, <ul>, <var>

Supported by the following JavaScript objects:

document, image, link, textarea


Tips and Notes

Browser differences: Internet Explorer uses event.keyCode to retrieve the character that was pressed and Netscape/Firefox/Opera uses event.which.

Example

In this example the user cannot type numbers into the input field:

<html>
<body>
<script type="text/javascript">
function noNumbers(e)
{
var keynum;
var keychar;
var numcheck;
if(window.event) // IE
  {
  keynum = e.keyCode;
  }
else if(e.which) // Netscape/Firefox/Opera
  {
  keynum = e.which;
  }
keychar = String.fromCharCode(keynum);
numcheck = /\d/;
return !numcheck.test(keychar);
}
</script>
<form>
<input type="text" 
onkeydown="return noNumbers(event)" />
</form>
</html>
JavaScript onkeydown Event Reviewed by 1000sourcecodes on 06:02 Rating: 5
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