使用PHP HTML错误进行验证

Question

Hello I've a simple Login Form,

I need to make it , if its empty , I want the Login button to be disabled otherwise its enabled I made.

<?php
        if($validate == "1")
        {
            echo '<input class="btn btn-primary btn-lg btn-block" type="submit" value="Login" />';
        }
        else
            {
                echo '<input class="btn btn-primary btn-lg btn-block" type="submit" value="Login" disabled="1" />';
            }
        ?>  

and in the main form code I made it gives $validate="1"; and $validate="0"; and it currently works IF i refresh the page without any text inside its disabled, but it nevers gets enabled if I wrote any text.

Answer 1

The code in your question is PHP code and PHP is only evaluated on server side (ie, on loading a page).

I suppose you want something which validates on client side - here you have to use JavaScript.

Answer 2

Thanks @MrTux for the idea <3 .

function validate(){
    if ($('#name').val().length   >   0   &&
        $('#password').val().length  >   0) {
        $("input[type=submit]").prop("disabled", false);
    }
    else {
        $("input[type=submit]").prop("disabled", true);
    }
}

Solved my problem!! you need to use JQuery library to make it work :).