Babel timing

[![Build status][ci-badge]][ci]
[![Npm version][npm-version-badge]][npm]

Measure Babel compilation time file by file, plugin by plugin.


Profile Babel when your application or your tests take ages to build.

Note: this tool is in version 0, any minor release might introduce breaking changes.

Installation

``bash
npm i babel-timing -D
yarn add babel-timing -D
`

Usage

$3

`bash
babel-timing path/to/file-1.js path/to/file-2.js
babel-timing path/to/file-*.js
babel-timing path/to/entrypoint.js --follow-imports
`

$3

`js
const { babelTiming } = require('babel-timing');
const results = await babelTiming(['path/to/file.js'], options);
`

$3

Profile Babel during the actual Webpack bundling process.

1. Import babel-timing/webpack/plugin to Webpack configuration:

`js
const BabelTimingPlugin = require('babel-timing/webpack/plugin');
`

2. Add customize option to the existing babel-loader configuration:

`js
module: {
rules: [
{
test: /\.m?js$/,
use: {
loader: 'babel-loader',
options: {
customize: require.resolve(
'babel-timing/webpack/babel-loader-customize'
),
},
},
},
];
}
`

3. Add babel-timing/webpack/plugin plugin _(accepts the [render options][render-options])_:

`js
plugins: [new BabelTimingPlugin()];
`

...with options _(accepts output and outputPath options)_:

`js
plugins: [
new BabelTimingPlugin({ output: 'json', outputPath: './results.json' }),
];
`

4. Delete babel-loader cache at ./node_modules/.cache/babel-loader/

5. Start Webpack bundling process and wait for results

$3

Profile Babel while running your actual Jest tests.

1. Add the following transform and reporters entries to the existing Jest configuration:

`js
{
transform: {
'^.+\\.jsx?$': 'babel-timing/jest/transformer'
},
reporters: [
'default',
'babel-timing/jest/reporter'
]
}
`

...with reporter's options _(accepts the [render options][render-options])_:

`js
{
reporters: [
'default',
[
'babel-timing/jest/reporter',
{ output: 'json', outputPath: './results.json' },
],
];
}
`

2. Run tests with --no-cache option

$3

- Hops

Options

#### babelConfig / --babel-config

Type: string | false

Default: false

Path to a custom babel configuration file. By default Babel will try to load any existing valid configuration file.

#### followImports / --follow-imports

Type: bool

Default: false

Follow imported files/modules and run babel-timing against them.

#### include / --include

Type: string[] _(cli accepts a string containing a comma-separated list)_

Default: ['**']

Include paths (imported ones also) according to the provided glob patterns.

#### exclude / --exclude

Type: string[] _(cli accepts a string containing a comma-separated list)_

Default: ['/node_modules/']

Exclude paths (imported ones also) according to the provided glob patterns.

#### resolveMainFields / --resolve-main-fields

Type: string[] _(cli accepts a string containing a comma-separated list)_

Default: ['browser', 'module', 'main']

When importing from an npm package this option will determine which fields in its package.json are checked.

#### resolveExtensions / --resolve-extensions

Type: string[] _(cli accepts a string containing a comma-separated list)_

Default: ['.js', '.jsx', '.mjs', '.ts']

Attempt to resolve these extensions in order. Any other extension won't be considered.

#### --read-results (CLI only, for Node use [render API][render-api])

Type: string

Default: undefined

Skip compilation and render existing results from file at specified path.

$3

#### output / --output

Type: string

Default: "return" ("console" when called via CLI or integrations)

Options: "return", "console", "json"

Make babel-timing results available as:

- "return" return results' object
- "console" render results in console
- "json" save results as babel-timing-results.json

#### outputPath / --output-path

Type: string

Default: "./babel-timing-results.json"

Path of output file in case output option is set to "json".

#### paginationSize / --pagination-size

Type: number

Default: 10

Number of entries displayed in a page when rendering "console" output.

#### aggregateBy / --aggregate-by

Type: string

Default: "files"

Options: "files", "plugins"

Output results aggregated by files or plugins.

#### expandPackages / --expand-packages

Type: bool

Default: false

Expand results relative to node_modules packages file by file.

How it works

Compile files with Babel 7 and get collect compilation info through [wrapPluginVisitorMethod][wrappluginvisitormethod-docs] Babel config option.

$3

Compilation info are by default extracted into the following data structure:

`typescript
type ResultList = {
name: string; // file name
time: number; // total compilation time
// compilation info by babel plugin
plugins: {
name: string;
time: number;
timePerVisit: number;
visits: number;
}[];
}[];
`

Notes

This tool started as an attempt of measuring the time taken by Babel while running transpiled tests and compiling Webpack applications.

The main difficulty of monitoring Babel while running the aforementioned tools, consists of relating the wrapPluginVisitorMethod calls to the files actually being compiled.

Any further idea/contribution to get to a better Babel profiling solution is welcome.

Manual tests :)

`bash
node cli.js __fixtures__/file-1.js
node cli.js __fixtures__/file-1.js __fixtures__/file-2.js
node cli.js __fixtures__/*.js
node cli.js __fixtures__/entry.js --follow-imports
`

API's

These API's are meant to integrate babel-timing with any bundler/tool using Babel.

$3

Timer class returns timer instances used to hook Babel's [wrapPluginVisitorMethod][wrappluginvisitormethod-docs], keep track of transform times and return a [ResultList][resultlist] entry object for a given file.

`js
const { Timer } = require('babel-timing');
const timer = new Timer(fileName);

// This is the function to be provided to Babel's "wrapPluginVisitorMethod" option
timer.wrapPluginVisitorMethod;

// Called after Babel transformations, returns "Results" object for given file
timer.getResults();
`

$3

Utility function meant to temporarily store Timer instances into a Node module while Babel compiles.

`js
const { timersCollection } = require('babel-timing');

// Returns Timer instance for given file. Creates a new Timer instance if no timer for given file is found
timersCollection.getFile(fileName);

// Returns an array containing all the stored Timer instances
timersCollection.getAll();

timersCollection.clear();
`

$3

Accepts a ResultList array and renders an interactive CLI visualisation or outputs a JSON file of it.

`js
const { render } = require('babel-timing');
render(babelTimingResults, { options });
`

Accepts the [render options][render-options].

Thanks to

- babel-minify’s timing plugin
- Facebook fbt's timing plugin
- This Stack Overflow's question/answers
- Xing Hops team

Todo

- Add csv output option
- Provide a wider set of integrations (rollup, babelify, parcel`, ...)
- Improve existing integrations
- Consider versioning results JSON data shape
- Consider splitting standalone feature from core and integrations

[ci-badge]: https://travis-ci.org/toomuchdesign/babel-timing.svg?branch=master
[ci]: https://travis-ci.org/toomuchdesign/babel-timing
[npm]: https://www.npmjs.com/package/babel-timing
[npm-version-badge]: https://img.shields.io/npm/v/babel-timing.svg
[wrappluginvisitormethod-docs]: https://babeljs.io/docs/en/options#wrappluginvisitormethod
[render-options]: #render-options
[resultlist]: #resultList
[render-api]: #renderresultlist-options