Pass parameters to javascript using wp_localize_script

I have read a half-dozen examples of how to pass parameters to javascript and they all describe the process in a very similar manner but don’t speak to one event: how does the javascript code actually get called? I have seen several examples where the code is tested in $document.ready, but can’t get them to work.

Here is my php code:

$base_id = 'id_'.wp_create_nonce("postlister");
$url = $_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI'];
$parms = array(
    'url'       => $url,
    'action'    => $action,
    'base_id'   => base_id );
wp_localize_script(self::slug.'-postlister', 'postlister_parms', $parms);

and m jQuery code:

jQuery(document).ready(function ($) {
    if (postlister_parms !== undefined) {
        var parms = postlister_parms;
        $.diagnostic('postlister loaded');
    }
});

When the jQuery code executes, postlister_parms is undefined.

Please help me spot what I am obviously missing.