Finding if a String is appears in Another Stirng

<html>
<head>
    <title>Regular Expression</title>
</head>
<body>
    <form name = "form">
        Str1: <input type = "text" name = "str1" />
        Str2: <input type = "text" name = "str2" />
        <input type = "submit" value ="Str2 in Str1?" onClick = "alert(new RegExp(form.str2.value).test(form.str1.value));" />
    </form>
</html>