Browser API Monitor

• Available in Chrome Web Store as API Monitor

If you're web developer and want to assess implementation correctness - this tool adds additional panel to the browser’s DevTool that enables to see scheduled timeouts and active intervals, as well as to review and navigate to initiators of: eval, setTimeout, setInterval, requestAnimationFrame, requestIdleCallback and their terminator functions.

Allows:

• to measure callback execution self-time.
• to see requestAnimationFrame callback request frame rate.
• visit every function in the call stack (if available), bypass or pause while debugging.
• detect eval function usage, see its argument and return value, same for setTimeout and setInterval when called with a string instead of a function.
• for every mounted video or audio media element's to see it’s state and properties.

Helps to spot:

• incorrect timeout delay.
• bad handler for terminator function.
• terminating non-existing or elapsed timeout.

Motivation:

• To expedite issues discovery.

Wrapped native functions:

• eval (by default off)
• setTimeout
• clearTimeout
• setInterval
• clearInterval
• requestAnimationFrame
• cancelAnimationFrame
• requestIdleCallback
• cancelIdleCallback

Note

While measuring performance of your code – consider disabling this extension as it may affect the results.

Example

Build requirements

• OS: Linux
• Node: 22.14.0 (LTS)
• Deno 2.2.12

Build instructions

make install  # install dependencies
make dev      # build in development mode and watch for changes
make prod     # build in production mode and make extension.chrome.zip