babel-plugin-console-perf v0.0.3

babel-plugin-console-perf

A babel plugin to simplifies the usage of profiling in JS functions. I got this idea when browsing documentation on various console methods, and discovered that there's a console.profile/profileEnd function that automatically starts and stops the JavaScript profiler for a particular region inside the function. I wanted to make this as seamless as possible.

Note: Alpha quality program. Use with caution, and never use this to production

Usage

1. Install the plugin using npm install --save-dev babel-plugin-console-perf
2. Add the plugin console-perf to your .babelrc
3. Add a comment // profile in the function you want to profile
4. Open the JS console in your browser, and navigate to the profiling tab. Note that on latest Chrome (Canary is what I generally use) the tool has been moved into the "more tools" section. This is not the Performance tab, by the way.
5. Load the page which calls the function where you added comment.

That should record individual profiles for each of the runs in case the function gets called multiple times.

Here's a video of the usage in action: console-perf-demo

Will try to put up a GIF as and when I get a chance.

If there are return statements, it checks to see if there are statements/expressions there, and then re-assigns them to variables and returns the variable instead. This ensures that the statements/expressions are also profiled. For instance:

function getHash () {
  // profile
  const a = 42;

  return heavyCryptoFunction({ key: a });
}

gets converted to:

function getHash () {
  console.profile('getHash');
  const a = 42;

  const hash = heavyCryptoFunction({ key: a});
  console.profileEnd();
  return hash;
}

instead of:

function getHash () {
  console.profile('getHash');
  const a = 42;

  console.profileEnd();
  return heavyCryptoFunction({ key: a });
}

which misses out on profiling a potentially CPU-heavy function.

Checkout other console-based plugins that I wrote:

babel-plugin-console-groupify

babel-plugin-transform-console-log-variable-names