How to do a php validation check for an input outside of a form
<p>I have an input outside of a form that I do validation with javascript, however I want back-end validation as well. The input I am referring to is basically an entry way to see a registration form. When the input value matches the value within the javascript it shows the registration form. </p>

<p>All I want is to figure out a way within my php code to check to see if the value of the input does not match the value within the php code, the person cannot submit the form.</p>

<p>Everything I have seen while trying to search for this only shows items within the same form. Does anyone have any idea how I would do this?</p>

<p>Let's say I want the php code to check to see if the value of the validate input = Entry, then I can submit the form.</p>

<pre><code>&lt;div id="validate"&gt;
            &lt;label&gt;Please provide your code&lt;/label&gt;
            &lt;input type="text" id="validate-input"&gt;
        &lt;/div&gt;
        &lt;form action="" method="POST" id="register"&gt;
&lt;?php if (isset($error)){
    echo $error, '&lt;br&gt;';
}?&gt;
            &lt;div class="field"&gt;
                &lt;label for="firstname"&gt;First Name&lt;/label&gt;
                &lt;input type="text"  class="inputbar" name="firstname" value="&lt;?php echo escape(Input::get('firstname')); ?&gt;" required&gt;
            &lt;/div&gt;
            &lt;div class="field"&gt;
                &lt;label for="lastname"&gt;Last Name&lt;/label&gt;
                &lt;input type="text" class="inputbar" name="lastname" value="&lt;?php echo escape(Input::get('lastname')); ?&gt;" required&gt;
            &lt;/div&gt;
&lt;input id="signinButton" type="submit" value="Register"&gt;
&lt;/form&gt;
</code></pre>