reactotron-core-client/src/stopwatch.ts

Grants Reactotron clients the ability to talk to a Reactotron server.

/// <reference types="node" />

declare const global: any

const hasHirezNodeTimer =
  false &&
  typeof process === "object" &&
  process &&
  process.hrtime &&
  typeof process.hrtime === "function"

// the default timer
// eslint-disable-next-line @typescript-eslint/no-unused-vars
const defaultPerformanceNow = (started?: number) => Date.now()

// try to find the browser-based performance timer
const nativePerformance =
  typeof window !== "undefined" &&
  window &&
  (window.performance || (window as any).msPerformance || (window as any).webkitPerformance)

// the function we're trying to assign
let performanceNow = defaultPerformanceNow

// accepts an already started time and returns the number of milliseconds
let delta = (started: number) => performanceNow() - started

if (hasHirezNodeTimer) {
  performanceNow = process.hrtime as any
  delta = (started) => performanceNow(started)[1] / 1000000
} else if (global.nativePerformanceNow) {
  // react native 47
  performanceNow = global.nativePerformanceNow
} else if (nativePerformance) {
  // browsers + safely check for react native < 47
  performanceNow = () => nativePerformance.now && nativePerformance.now()
}

/**
 * Starts a lame, low-res timer.  Returns a function which when invoked,
 * gives you the number of milliseconds since passing.  ish.
 */
export const start = () => {
  //  record the start time
  const started = performanceNow()
  return () => delta(started)
}