paulirish
Numbers not matching summary
Hello -
I am trying to automate some performance measurements and I want to get the results from the Summary chart in DevTools. Specifically, I am looking at the Scripting category.
I am running into an issue where the numbers between the devtools-timeline-model library and DevTools are different. In the attached profile file, I get 847.2ms in DevTools/Chrome while I get 833.98ms using the devtools-timeline-model library.
Here is the code snippet that I am using to get the total time spent in Scripting:
(async () => { const puppeteer = require("puppeteer"); const devtools = require("devtools-timeline-model"); const fs = require("fs"); const format = require("date-format"); const browser = await puppeteer.launch({ headless: false }); const page = await browser.newPage(); const client = await page.target().createCDPSession(); const traceFile = "trace-" + format('yyyyMMddhhmmss', new Date()) + ".json"; await client.send("Performance.enable"); await page.tracing.start({ path: traceFile }); await page.goto('https://www.msn.com'); await page.tracing.stop(); var events = fs.readFileSync(traceFile, "utf8"); var model = new devtools(events); var summary = model.topDownGroupBy("Category").children; if(summary.has("scripting")) { console.log(summary.get("scripting").totalTime); } await browser.close(); })();
Why would I get different numbers between what the code prints to console vs. when I open the same capture file in DevTools?
