Month: December 2012

Closure Compiler externs updates

Just pushed fixes and updates to my Closer Compiler externs for underscore, and created a repo for Qunit externs (which is probably not of any use to anyone, but is used by for testing accuracy/completeness of underscore externs).

underscore-js-externs

  • Externs for latest underscore (1.4.3).
  • Some fixes to 1.3.3 externs, indicating that more methods may return wrapped objects (this is still incomplete).
  • Tests for externs file completeness/accuracy by running underscore’s own qunit tests through closure compiler. The output (using advanced compilation) is nasty and contains a lot of errors, but most of them are irrelevant. Some do point to legitimate issues, mostly related to uncommon ways of passing arguments to various methods.

qunit-js-externs

  • Externs missing for `throws`, callbacks, and configuration. Mostly complete.

Exploring Chrome’s timeline panel

Subsequent to some performance issues with a few Backbone apps, I spent some time digging further into Google Chrome’s timeline panel, and specifically the memory view that shows allocated memory, and breaks down the number of DOM nodes held in memory.

Some tests/demos along with provisional findings are provided here: chrome timeline exploration. The official documentation for Chrome’s dev tools is getting better, but could still use improvement. Hopefully this will go some way to providing a bit more insight into what’s going on, what different numbers mean, and what sort of behaviour you can expect from common scenarios.

As I’m nowhere near an expert of Chrome’s internals nor on memory profiling in general, any suggestions or corrections are more than welcome (pull requests or whatever).