Untitled

<!DOCTYPE html>
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<html>
    <head>
        <title>TODO supply a title</title>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
    </head>
    <body>
        <form name="forma" action="nekiskript.php" method="GET" onsubmit="return proveriIme(document.getElementById('ime')) &&  proveriPrezime(document.getElementById('prezime'));">
            <fieldset>
                <legend>Podaci o korisniku</legend>
                <table>
                    <tbody>
                        <tr>
                            <td>Ime</td>
                            <td> <input type="text" id="ime" name="ime" value="" /> </td>
                        </tr>
                        <tr>
                            <td>Prezime</td>
                            <td> <input type="text" id="prezime" name="prezime" value="" /> </td>
                        </tr>
                        <tr>
                            <td>E-mail</td>
                            <td> <input type="email" name="email" value="" /> </td>
                        </tr>
                        <tr>
                            <td>Sifra</td>
                            <td> <input type="password" name="sifra" value="" /> </td>
                        </tr>
                        <tr>
                            <td>Potvrdi sifru</td>
                            <td> <input type="password" name="potSifre" value="" /> </td>
                        </tr>
                        <tr>
                            <td>Pol</td>
                            <td>
                                <select name="pol">
                                    <option>Musko</option>
                                    <option>Zensko</option>
                                    <option>Ostalo</option>
                                    <option>Ne zelim da se izjasnim</option>
                                </select>
                            </td>
                        </tr>
                        <tr>
                            <td>2+3</td>
                            <td> <input type="text" name="verifikacija" value="" /> </td>
                        </tr>
                        <tr>
                            <td><input type="reset" value="Ponisti unos" /> </td>
                            <td> <input type="submit" value="Posalji podatke" /> </td>
                        </tr>
                    </tbody>
                </table>

            </fieldset>
        </form>

        <script>
            var a=1;
            console.log(isNaN(a));// vraca true ako nije broj i vraca false ako je parametar broj

            function proveriIme(param){
                if(isNaN(param.value) || param.value!==null || param.value!==""){
                    alert(isNaN(param.value));
                }else{
                    alert(isNaN(param.value));
                    return false;
                }

            }

            function proveriPrezime(param){
                if(isNaN(param.value) || param.value!==null || param.value!==""){
                    alert(isNaN(param.value));
                }else{
                    alert(isNaN(param.value));
                    return false;
                }

            }
        </script>
    </body>
</html>