Martin Paul Eve bio photo

Martin Paul Eve

Professor of Literature, Technology and Publishing at Birkbeck, University of London and Technical Lead of Knowledge Commons at MESH Research, Michigan State University

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JavaScript eval String.fromCharCode encoder

Cite as: Martin Paul Eve, "JavaScript eval String.fromCharCode encoder", https://eve.gd, , https://doi.org/10.59348/29wts-5q506.

Here is a nice tool for encoding JavaScript into eval(String.fromCharCode(x,x,x)) format. A full HTML page is listed here, or you can try it out live at the bottom of this post.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
	<title>Javascript Eval Encoder</title>
	<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"/>
	<script type="text/javascript">
		function encode_to_javascript() {
			var input = document.getElementById('inputtext').value;

			var output = 'eval(String.fromCharCode(';

			for(pos = 0; pos < input.length; pos++) {
				output += input.charCodeAt(pos);
	
				if(pos != (input.length - 1)) {
					output += ",";
				}
			}

			output += '))';

			document.getElementById('result').innerHTML = output;
			return 0;
		}
	</script>
	</head>
	<body>
		<textarea id="inputtext" rows="10" cols="50"></textarea><br/>
		<input type="submit" value="Encode" onclick="javascript:encode_to_javascript()"/>
		<br/><span id="result"></span>
	</body>
</html>

Encode