BOOMR.plugins. CT

The CT plugin tests how long an item stays in the browser's cache.

Given a URL, this plugin loads the specified URL and measures how long it took to load.

You can use the results of this plugin to determine how cacheable a URL is across browsers and over time.

For information on how to include this plugin, see the Building tutorial.


This plugin requires a server-generated JavaScript file that calls BOOMR.plugins.CT.loaded with the server's timestamp.

This file is specified as CT.cached_url and should return an application/javascript file with contents similar to:

BOOMR.plugins.CT.loaded(12345); // server-generated timestamp

Beacon Parameters

This plugin adds the following parameters to the beacon:

  • cch.ce: Time when the cached item started to load
  • Load time of cached item (ms)
  • Server timestamp



Initializes the plugin.


Name Type Description
config object


Name Type Description
CT.cached_url string

URL to load


BOOMR.plugins.CT The CT plugin for chaining