JQuery :: Form - On Focus Change Type To Password

$(this).attr('type', "password");
(this).attr('type') = 'password'
neither of these work, am I doing something wrong?

Full code:
<div id="register-form">
<input type="text" class="reginput" name="username" defaultVal="username / URL" />
<input type="text" class="reginput" name="password" defaultVal="password"/>
<input type="text" class="reginput" name="e-mail" defaultVal="e-mail"/>
<div class="button-form">Create my free account</div>
</div>

$('.reginput').each( function () {
$(this).val($(this).attr('defaultVal'));
$(this).css({color:'#699fe7'});
});
$('.reginput').focus(function(){
if ( $(this).val() == $(this).attr('defaultVal') ){
$(this).val('');
$(this).css({color:'#2d5891'});
$(this).attr('type', "password");
//if ( $(this).attr('name') == 'password') { $(this).attr('type') = 'password' }
}});
$('.reginput').blur(function(){
if ( $(this).val() == '' ){
$(this).val($(this).attr('defaultVal'));
$(this).css({color:'#699fe7'});
}});