Get the speed index from chrome dev tool timeline files
npm install speedline-coreThis is the core module for speedline, without any CLI dependencies. See speedline for the CLI.
``bash`
$ npm install speedline
`js
const speedline = require('speedline-core');
speedline('./timeline').then(results => {
console.log('Speed Index value:', results.speedIndex);
});
`
#### speedline(timeline [, opts])
* (string | object[]) timelineopts
* (object)
Returns a (Promise) resolving with an object containing:
* beginning (number) - Recording start timestampend
* (number) - Recording end timestampspeedIndex
* (number) - speed index value.perceptualSpeedIndex
* (number) - perceptual speed index value.first
* (number) - duration before the first visual change in ms.complete
* (number) - duration before the last visual change in ms.duration
* (number) - timeline recording duration in ms.frames
* (Frame[]) - array of all the frames extracted from the timeline.
timeline parameter:
* string - the parameter represents the location of the of file containing the timeline.array
* - the parameter represents the traceEvents content of the timeline file.
opts parameter:
* timeOrigin: Provides the baseline timeStamp, typically navigationStart. Must be a monotonic clock timestamp that matches the trace. E.g. speedline('trace.json', {timeOrigin: 103205446186})fastMode
* : If the elapsed time and difference in similarity between two screenshots are small, fastMode will skip decoding and evaluating the frames between them.include
* : Specifies which speed indexes to compute, can be one of all|speedIndex|perceptualSpeedIndex, defaults to all.
#### Frame
Object representing a single screenshot.
* frame.getHistogram(): (number[][]) - returns the frame histogram. Note that light pixels informations are removed from the histogram, for better speed index calculation accuracy.frame.getTimeStamp()
* : (number) - return the frame timestamp.frame.getImage()
* : (Buffer) - return the frame content.frame.getProgress()
* : (number) - return the frame visual progress.frame.getPerceptualProgress()`: (number) - return the frame perceptual visual progress.
*
MIT © Pierre-Marie Dartus