以下の内容の HTML ファイルを適当なエディターで作る。
<HTML>
<HEAD>
<TITLE>
eval
</TITLE>
<SCRIPT LANGUAGE = "JavaScript">
<!--
function calc(obj)
{
obj.result.value = eval(obj.calculate.value);
}
// -->
</SCRIPT>
</HEAD>
<BODY>
<FORM NAME = "calcform">
<INPUT TYPE = "text" NAME = "calculate" SIZE = 20>
<INPUT TYPE = "button" NAME = "docalc" VALUE = "do calculate" onClick = "calc(this.form)">
<BR>
<INPUT TYPE = "text" NAME = "result" SIZE = 20>
</FORM>
</BODY>
</HTML>