Question

I’ve come across this many times ( I don’t want to use ‘input type button’ here ) why oh why the ‘onclick’ doesn’t call the function check(); ? The page still submits even when the fields are empty. Thank you for your comments.

Javascript:

function check() { 
    var name =  document.getElementById('username_res');
    var passw_old =  document.getElementById('passw_reset_old');
    var passw_new =  document.getElementById('passw_reset');
    var button_res = document.getElementById('sub_res');

    if ((name.val() == "") && (passw_old.val().length == "") && (passw_new.val().length == "")) { 
        button_res.disabled = true; 
    } else {
        button_res.disabled = false;
    }
}

HTML:

<form id="passw_res" name="passw_res" method="post" action="pass_reset.php">
<fieldset style="width:300px"><br/>
<legend id="pass_legend" align="left">Password reset</legend><br/>
<input type="text" id="username_res" name="username_res" maxlength="50" />
<input type="password" id="passw_reset_old" name="passw_reset_old" maxlength="16"/>
  <input type="password" id="passw_reset" name="passw_reset" maxlength="16"  />
  <input type="submit" value="submit" id="sub_res" name="sub_res" onclick="check();"/>
 </fieldset>
  </form>

So…the page shouldn’t submit on empty fields – why does it submit ? Thanks..

Answer 1

Change your function to this:

function check() { 

    var name =  document.getElementById('username_res').value;
    var passw_old =  document.getElementById('passw_reset_old').value;
    var passw_new =  document.getElementById('passw_reset').value;

    return ((name != '') && (passw_old != '') &&  (passw_new != ''));

}

You actually don’t have to change the onclick event to an onsubmit, just change it to onclick="return check();". You need to return false to the onclick event to prevent it from being fired.

You might want to add some visual enhancements to indicate why the form isn’t submitted. Otherwise it will be confusing to the visitor.