Simple js profiler.

profiler.ts

class Timer {
  start: number;
  constructor() {
    this.start = performance.now();
  }
  elapsed() {
    return performance.now() - this.start;
  }
}

export class Profiler {
  timers: Map<string, Timer> = new Map();
  totals: Map<string, Array<number>> = new Map();
  start(name: string) {
    if (this.timers.has(name)) {
      throw Error(`Timer ${name} already exists.`);
    }
    this.timers.set(name, new Timer());
  }
  stop(name: string) {
    const timer = this.timers.get(name);
    if (!timer) {
      throw Error(`Timer ${name} does not exist.`);
    }
    this.totals.set(name, [...(this.totals.get(name) || []), timer.elapsed()]);
    this.timers.delete(name);
  }
  print() {
    this.totals.forEach((value, key) => {
      // eslint-disable-next-line no-console
      console.log({
        name: key,
        count: value.length,
        time: value.reduce((a, b) => a + b, 0),
      });
    });
  }
}