javascript - Simple form validation -

post #1

how can validate simple form (checking empty field strings)?

                <p>please select gift certificate amount below. please enter name , gift certificate recipient's name. once click 'buy now' sent our paypal site complete purchase.</p>                      <form action="https://www.paypal.com/cgi-bin/webscr" method="post">         <input type="hidden" name="cmd" value="_s-xclick">         <input type="hidden" name="hosted_button_id" value="sdsafsdafsadfdsafsdafsadfsadfsadfasdfsadfsdaf">         <table width="100%">         <tr>             <td width="130"><input type="hidden" name="on0" value="amount"><p>amount</p></td>             <td><select name="os0">             <option value="option 1">$20.00</option>             <option value="option 2">$50.00</option>             <option value="option 3">$100.00</option>             </select></td>         </tr>         <tr>             <td><input type="hidden" name="on1" value="to:"><p>to (full name):</p></td>             <td><input type="text" name="os1" maxlength="60" size="30"></td>         </tr>         <tr>             <td><input type="hidden" name="on2" value="from:"><p>from (full name):</p></td>             <td><input type="text" name="os2" maxlength="60" size="30"></td>         </tr>         </table>          <table width="100%" style="margin-top: 10px;">             <tr>                 <td><input type="hidden" name="currency_code" value="cad">         <p><input type="image" src="button.jpg" border="0" name="submit" alt="paypal - safer, easier way pay online!"></p>         <img alt="" border="0" src="https://www.paypal.com/en_us/i/scr/pixel.gif" width="1" height="1"></td>                 <td align="right"><img src="../paypal_logo.jpg" alt="paypal" /></td>             </tr>         </table>         </form> 

post #2

function validate_form() { valid = true;

    if ( document.giftform.os1.value == "" )     {         alert ( "please fill in 'your name' box." );         valid = false;     }     return valid; } 

-=-=-=-= form

        <form action="https://www.paypal.com/cgi-bin/webscr" method="post" method="giftform" onsubmit="validate_form( )">         <input type="hidden" name="cmd" value="_s-xclick">         <input type="hidden" name="hosted_button_id" value="sdsafsdafsadfdsafsdafsadfsadfsadfasdfsadfsdaf">         <table width="100%">         <tr>             <td width="130"><input type="hidden" name="on0" value="amount"><p>amount</p></td>             <td><select name="os0">             <option value="option 1">$20.00</option>             <option value="option 2">$50.00</option>             <option value="option 3">$100.00</option>             </select></td>         </tr>         <tr>             <td><input type="hidden" name="on1" value="to:"><p>to (full name):</p></td>             <td><input type="text" name="os1" maxlength="60" size="30"></td>         </tr>         <tr>             <td><input type="hidden" name="on2" value="from:"><p>from (full name):</p></td>             <td><input type="text" name="os2" maxlength="60" size="30"></td>         </tr>         </table>          <table width="100%" style="margin-top: 10px;">             <tr>                 <td><input type="hidden" name="currency_code" value="cad">         <p><input type="image" src="button.jpg" border="0" name="submit" alt="paypal - safer, easier way pay online!"></p>         <img alt="" border="0" src="https://www.paypal.com/en_us/i/scr/pixel.gif" width="1" height="1"></td>                 <td align="right"><img src="../paypal_logo.jpg" alt="paypal" /></td>             </tr>         </table>         </form> 

is jquery option? there's nice validation tool http://docs.jquery.com/plugins/validation