Zizzamia/perfume.js

import { M, S, WP } from '../constants';
import { reportPerf } from '../reportPerf';
import { config } from '../config';

import { STEP_THRESHOLDS, getRating } from '../vitalsScore';

export const measureStep = (
  step: string,
  startMark: string,
  endMark: string,
) => {
  const stepMetricName = S + step;
  const startMarkExists = WP.getEntriesByName(M + startMark).length > 0;
  const endMarkExists = WP.getEntriesByName(M + endMark).length > 0;
  if (
    !endMarkExists ||
    !startMarkExists ||
    !config.steps ||
    !config.steps[step]
  ) {
    return;
  }

  const { maxOutlierThreshold, vitalsThresholds } =
    STEP_THRESHOLDS[config.steps[step].threshold];

  const stepMeasure = WP.measure(stepMetricName, M + startMark, M + endMark);

  // checking to ensure stepMeasure is defined - it can be undefined
  // if measure is called on a mark that has already been measured and cleared
  if (!stepMeasure) {
    return;
  }

  const { duration } = stepMeasure;
  if (duration <= maxOutlierThreshold) {
    const score = getRating(duration, vitalsThresholds);
    // Do not want to measure or log negative metrics
    if (duration >= 0) {
      reportPerf(
        'userJourneyStep',
        duration,
        score,
        { stepName: step },
        undefined,
      );
      WP.measure(`step.${step}_vitals_${score}`, {
        start: stepMeasure.startTime + stepMeasure.duration,
        end: stepMeasure.startTime + stepMeasure.duration,
        detail: {
          type: 'stepVital',
          duration,
        },
      });
    }
  }
};