@dash0/sdk-web/dist/modules/transport/batcher.js

Dash0's Web SDK to collect telemetry from end-users' web browsers

import { onLastChance } from "../utils/on-last-chance";
import { doc } from "../utils";
import { setTimeout } from "../utils/timers";
const SCHEDULE_DELAY_MILLIS = 1000;
const MAX_QUEUE_SIZE = 15;
export function newBatcher(sendInternal) {
    const queuedItems = [];
    let pendingFlushTimeout;
    // We attempt batching of messages to be more efficient on the client, network and
    // server-side. While the connection is either a persistent HTTP 2 connection or
    // an HTTP 1.1 connection with keep-alive, there is still some overhead involved
    // in having many small messages.
    //
    // For this reason we attempt batching. When batching we must be careful to
    // force a transmission when the document is unloaded.
    onLastChance(flush);
    return {
        send(item) {
            if (isWindowHidden()) {
                // We cannot guarantee that we will ever get time to transmit data in a batched
                // format when the window is hidden, as this might occur while the document is
                // being unloaded. Immediately force a transmission in these cases.
                sendInternal([item]);
                return;
            }
            queuedItems.push(item);
            if (queuedItems.length >= MAX_QUEUE_SIZE) {
                flush();
            }
            else if (pendingFlushTimeout == null) {
                pendingFlushTimeout = setTimeout(flush, SCHEDULE_DELAY_MILLIS);
            }
        },
    };
    function flush() {
        if (pendingFlushTimeout != null) {
            clearTimeout(pendingFlushTimeout);
            pendingFlushTimeout = null;
        }
        if (queuedItems.length > 0) {
            sendInternal(queuedItems.slice());
            queuedItems.length = 0;
        }
    }
}
function isWindowHidden() {
    return doc?.visibilityState !== "visible";
}