Can't find variable is_single in my jQuery plugin

Question

I converted a jQuery plugin into a Wordpress one where I reference the method is_single():

if (is_single()) {
    // Do something
}

BTW, this code is in my js file. Is that the mistake I'm making?

The plugin installs and runs correctly, but, I get an error saying is_single can't be found. How do I fix this? What am I doing wrong exactly?

Answer 1

The easiest way in WP to write php into JS is using wp_footer

function sse246626_js() {
 if(is_single()) {
  echo '<script type="text/javascript">';
   echo 'jQuery(document).ready(function($) {';
    echo '$("#mydiv").hide();';
   echo '});';
  echo '</script>';
 }
}
add_action('wp_footer', 'sse246626_js');

This way gives you access to the WP functions as you need, there are probably better ways of doing it if you have lots of JS (php file as a JS file) but it gets slightly complicated as you need to load the WP functions to be used in the file.