@zendesk/react-measure-timing-hooks/cjs/v3/ensureTimestamp.js

react hooks for measuring time to interactive and time to render of components

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.adjustTimestampBy = exports.ensureTimestamp = void 0;
exports.getEpochCorrectedForDrift = getEpochCorrectedForDrift;
const JUST_CREATED_THRESHOLD_MS_AGO = 10;
/**
 * Ensures that the input timestamp object has both epoch and performance.now() time.
 * If no input is provided, it generates a new timestamp with the current time.
 *
 * why store both timestamps?:
 * - epoch time: for reporting absolute time / correlating with backends
 * - durations: for calculating durations between two timestamps, performance.now() time makes more sense
 * - both are needed to correctly calculate a drift-adjusted epoch time
 *
 * @param input - Partial timestamp object that may contain either epoch or now or both.
 * @returns Full timestamp object with both epoch and performance.now() time.
 */
const ensureTimestamp = (input) => {
    const inputEpoch = input?.epoch;
    const inputNow = input?.now;
    const hasInputEpoch = typeof inputEpoch === 'number';
    const hasInputNow = typeof inputNow === 'number';
    if (hasInputEpoch && hasInputNow) {
        return input;
    }
    if (hasInputEpoch) {
        const differenceFromNow = Date.now() - inputEpoch;
        return {
            epoch: inputEpoch,
            now: Math.abs(differenceFromNow) < JUST_CREATED_THRESHOLD_MS_AGO
                ? performance.now()
                : performance.now() + differenceFromNow,
        };
    }
    if (hasInputNow) {
        const elapsedTimeSinceInput = performance.now() - inputNow;
        const epoch = Date.now() - elapsedTimeSinceInput;
        return {
            epoch,
            now: inputNow,
        };
    }
    // no data provided, use current time
    return {
        now: performance.now(),
        epoch: Date.now(),
    };
};
exports.ensureTimestamp = ensureTimestamp;
// below inspired by Datadog SDK
// https://github.com/DataDog/browser-sdk/blob/16efff71b42530ead10400eb23c096b54e83fad4/packages/core/src/tools/utils/timeUtils.ts#L23-L30
/**
 * Navigation start slightly change on some rare cases
 */
let navigationStart;
function getNavigationStart() {
    if (navigationStart === undefined) {
        navigationStart = performance.timing.navigationStart;
    }
    return navigationStart;
}
/**
 * Why do we need to account for drift?
 * - monotonic clock (performance.now()) is not guaranteed to be in sync with wall clock time (Date.now())
 * - Earth’s rotation speed is not constant
 * - browser bugs cause the monotonic clock to not tick when the computer is asleep or when the process is throttled
 * @see
 * - https://github.com/w3c/performance-timeline/issues/206
 * - https://dev.to/noamr/when-a-millisecond-is-not-a-millisecond-3h6
 * - https://issues.chromium.org/issues/41450546
 */
function getEpochCorrectedForDrift({ epoch, now }) {
    // two different time origins
    const calculatedTimeOrigin = epoch - now;
    const navigationStartEpoch = getNavigationStart();
    // apply correction only for positive drift
    if (calculatedTimeOrigin > navigationStartEpoch) {
        return Math.round(calculatedTimeOrigin + now);
    }
    return Math.round(navigationStartEpoch + now);
}
const adjustTimestampBy = (timestamp, adjustment) => ({
    epoch: timestamp.epoch + adjustment,
    now: timestamp.now + adjustment,
});
exports.adjustTimestampBy = adjustTimestampBy;
//# sourceMappingURL=ensureTimestamp.js.map