overcentric/dist/activity.js

Overcentric watches your website, product, and users - and tells you what matters and what to do about it.

import { log } from "./config";
// What counts as "real" user activity. These are the signals that should keep a
// session (and an in-progress recording) alive. A tab that is merely open and
// focused but receives none of these is considered idle.
const ACTIVITY_EVENTS = [
    "mousedown",
    "mousemove",
    "keydown",
    "scroll",
    "touchstart",
    "click",
];
// Coalesce bursts of activity (e.g. mousemove) so we don't run callbacks on
// every single event.
const THROTTLE_MS = 1000;
let initialized = false;
let lastActivity = Date.now();
let throttledUntil = 0;
const listeners = new Set();
function onActivity() {
    const now = Date.now();
    lastActivity = now;
    if (now < throttledUntil)
        return;
    throttledUntil = now + THROTTLE_MS;
    listeners.forEach((fn) => {
        try {
            fn();
        }
        catch (e) {
            log.debug(`Activity listener threw: ${e}`);
        }
    });
}
/**
 * Start listening for real user-input events. Safe to call multiple times;
 * listeners are only attached once.
 */
export function initActivityTracking() {
    if (initialized || typeof window === "undefined")
        return;
    initialized = true;
    lastActivity = Date.now();
    ACTIVITY_EVENTS.forEach((evt) => {
        document.addEventListener(evt, onActivity, {
            capture: true,
            passive: true,
        });
    });
    log.debug("Activity tracking initialized");
}
/**
 * Register a callback that fires (throttled) whenever genuine user activity
 * occurs. Returns an unsubscribe function.
 */
export function onUserActivity(fn) {
    listeners.add(fn);
    return () => listeners.delete(fn);
}
/** Milliseconds since the last detected user activity. */
export function timeSinceLastActivity() {
    return Date.now() - lastActivity;
}
/** Timestamp (ms) of the last detected user activity. */
export function getLastActivity() {
    return lastActivity;
}