A diagnostic, cross-browser performance testing agent.

When you run the agent, it will load the page in the browser you chose and apply any special parameters you have provided. By default, it will store results for the test in a /results directory. Each test gets its own folder with the date prefixed, followed by a unique ID.

Inside the test folder, the following files are added:

• console.json - Console output from the page to look for warnings, JS errors, etc
• a video file showing the page load progression
• metrics.json - A collection of timing metrics collected from the browser during page load
• pageload.har - A har file of the page load
• resources.json - The resource timing API data for the page
• screenshot.png - A screenshot of the final page load
• /filmstrip - A collection of screenshots during the page load that could be used for a filmstrip

A full list of parameters can be printed to the terminal by running npx . --help. Here's what's currently supported:

Options: -u, --url <url> URL to run tests against -b, --browser <browser_name> Browser to run tests with (choices: "chrome", "chrome-beta", "canary", "edge", "safari", "firefox", default: "chrome") -h, --headers <object> Any custom headers to apply to requests -c, --cookies <object> Any custom cookies to apply -f, --flags <string> A comma separated list of Chromium flags to launch Chrome with. See: https://peter.sh/experiments/chromium-command-line-switches/ --blockDomains <domains...> A comma separated list of domains to block (default: []) --block <substrings...> A comma-delimited list of urls to block (based on a substring match) (default: []) --firefoxPrefs <object> Any Firefox User Preferences to apply (Firefox only). Example: '{"network.trr.mode": 2}' --cpuThrottle <int> CPU throttling factor --connectionType <string> Network connection type. By default, no throttling is applied. (choices: "cable", "dsl", "4g", "3g", "3gfast", "3gslow", "2g", "fios", default: false) --width <int> Viewport width, in pixels (default: "1366") --height <int> Viewport height, in pixels (default: "768") --frameRate <int> Filmstrip frame rate, in frames per second (default: 1) --disableJS Disable JavaScript (default: false) --debug Output debug lines (default: false) --auth <object> Basic HTTP authentication (Expects: {"username": "", "password": ""}) (default: false) --timeout <int> Maximum time (in milliseconds) to wait for test to complete (default: 30000) --html Generate HTML report (default: false) --list Generate a list of test results as HTML (default: false) --help display help for command 

You can set a custom timeout by passing the desired timeout in milliseconds using the --timeout parameter. Defaults to 30000, or 30 seconds.

npx . -u https://www.example.com -b chrome --timeout 50000 

Browser support ✅ Edge ✅ Chrome 🚫 Safari ✅ Firefox

You can define custom cookies to be passed along to request when running your test using the -c or --cookies parameter.

Cookies must have a name and value passed. Optionally, you can also pass in either a URL or a domain and path. If none are passed, the script will default to using the test page url.

npx . -u https://www.example.com -b chrome -c '{"name": "foo", "value": "bar"}' 

npx . -u https://www.example.com -b chrome -c '[{"name": "foo", "value": "bar"}, {"name": "foo2", "value": "bar2"}]' 

npx . -u https://www.example.com -b chrome -c '{"name": "foo", "value": "bar", "domain":"www.example.com", "path":"/optim"}' 

Browser Support ✅ Edge ✅ Chrome ✅ Safari ✅ Firefox

You can run tests with JavaScript disabled to see the impact on performance by passing the --disableJS parameter like so:

npx . -u https://playwright.dev/ -b firefox --disableJS 

Browser Support ✅ Edge ✅ Chrome ✅ Safari ✅ Firefox

To test sites protected with HTTP authentication, you can pass the --auth parameter. It expects an object with a username and password like so:

npx . -u https://newsletter.www.example.com/admin -b safari --auth '{"username": "username", "password": "password"}' 

After checking out the code, you need to install all the dependencies:

npm install 

Telescope uses Playwright to control and manage individual browser engines. Telescope will automatically run npx playwright install to install Chrome, Firefox, Chrome Canary and Safari (webkit).

Note: Safari for MacOS Tahoe is now available in playwright@next version so we use that until it is available on the @latest channel.

To install Microsoft Edge or Chrome Beta playwright requires root privileges and will not automatically install them, all you have to do that is to run npx playwright install msedge chrome-beta from the command line (and provide root password).

Telescope uses ffmpeg to process the video and generate filmstrip images. You will need to have it installed on your machine.

For MacOS you can use homebrew to install it:

brew install ffmpeg 

You can run telescope from within a Node.js script:

import { launchTest } from '@cloudflare/telescope'; const result = await launchTest({ url: 'https://example.com', browser: 'chrome', width: 1920, height: 1080, timeout: 60000, }); if (result.success) { console.log(`Test completed: ${result.testId}`); console.log(`Results saved to: ${result.resultsPath}`); } else { console.error(`Test failed: ${result.error}`); }

All CLI options are supported as object properties. See Parameters section for available options.