trace event

index.js

const CDP = require('chrome-remote-interface');
const minimist = require('minimist');

const args = minimist(process.argv.slice(2), {
  alias: {port: 'p'},
  default: {port: 9222},
});

async function main() {
  const client = await CDP({port: args.port});
  if (!client.NodeTracing) {
    console.error(
        `The implementation doesn't support NodeTracing domain. Closing.`);
    client.close();
    return;
  }

  const cats = await client.NodeTracing.getCategories();
  console.log('supported categories:');
  for (const c of cats.categories) {
    console.log(' ', c);
  }

  // Events are emitted only after the timeout expires below (currently 5 sec).
  client.on('event', (message) => {
    console.log('event:', message.method);
    if (message && message.data && message.data.value) {
      for (const value of message.data.value) {
        console.log(value);
      }
    }
  });

  client.NodeTracing.tracingComplete(() => {
    client.close();
  });

  // `data` here is undefined somehow with Node 10.2.0. Use the client.on('event') above instead.
  client.NodeTracing.dataCollected((data) => {
    // for (const value of data.value) {
    //   if (value.cat !== 'v8' && value.cat !== 'node') {
    //     continue;
    //   }

    //   console.log('  pid:', value.pid);
    //   console.log('  tid:', value.tid);
    //   console.log('  ts:', value.ts);
    //   console.log('  ph:', value.ph);
    //   console.log('  dur:', value.dur);
    //   console.log('  cat:', value.cat);
    //   console.log('  name:', value.name);
    //   console.log('  args:', value.args);
    //   console.log();
    // }
  });

  await client.NodeTracing.start({
    traceConfig: {
      recordMode: 'recordContinuously',
      includedCategories: ['v8', 'node'],
    },
  });

  setTimeout(() => {
    client.NodeTracing.stop();
  }, 5000).unref();
}

main().catch(console.error);