Tracium

Tracium is the Google Lighthouse
tracing parser extracted into a stand-alone library.

Tracium is a modern alternative to Big Rig.
Tracium correctly parses modern Chrome Traces (generated by Chrome 66+).

Usage

Install:
``
$ npm install tracium
`

Use:

`js
const Tracium = require('tracium');
const traceJSON = JSON.parse(fs.readFileSync('./mytrace.json', 'utf8'));
const tasks = Tracium.computeMainThreadTasks(traceJSON, {
// |flatten| default to |false|. When false, only top-level tasks will be returned.
flatten: true,
});
`

Check out examples at //examples/ folder.

API

#### tracium.computeMainThreadTasks(traceJson[, options])
- traceJson <[Object]> A JSON of a Chromium trace
- options <[Object]> Set of options for trace processing
- flatten <[boolean]> Defaults to false. Whether to flatten tasks tree.
- returns: <[Array]<[Object]>> An array of tasks:
- kind <[string]> describes task attribution. Can be one of the following:
- 'parseHTML'
- 'styleLayout'
- 'paintCompositeRender'
- 'scriptParseCompile'
- 'scriptEvaluation'
- 'garbageCollection'
- 'other'
- startTime <[number]> monotonic start time in milliseconds
- endTime <[number]> monotonic end time in milliseconds
- duration <[number]> task duration in milliseconds, a.k.a. "wall time"
- selfTime <[number]> time spent in the task at the current level of the task tree
- event <[Object]> original trace event object associated with the task
- children <[Array]<[Task]>> an array of child tasks
- parent a parent task if any

Returns an array of tasks that belong to the main thread of the inspected page.
If flatten is passed to false, than only top-level tasks will be returned.

[Array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array "Array"
[boolean]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type "Boolean"
[Buffer]: https://nodejs.org/api/buffer.html#buffer_class_buffer "Buffer"
[function]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function "Function"
[number]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type "Number"
[Object]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object "Object"
[origin]: https://developer.mozilla.org/en-US/docs/Glossary/Origin "Origin"
[Promise]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise "Promise"
[string]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type "String"
[stream.Readable]: https://nodejs.org/api/stream.html#stream_class_stream_readable "stream.Readable"
[Error]: https://nodejs.org/api/errors.html#errors_class_error "Error"
[ChildProcess]: https://nodejs.org/api/child_process.html "ChildProcess"
[iterator]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols "Iterator"
[Element]: https://developer.mozilla.org/en-US/docs/Web/API/element "Element"
[Map]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map "Map"
[selector]: https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Selectors "selector"
[Serializable]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify#Description "Serializable"
[xpath]: https://developer.mozilla.org/en-US/docs/Web/XPath "xpath"
[UnixTime]: https://en.wikipedia.org/wiki/Unix_time "Unix Time"