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    3.1.9 • Public • Published

    ArtifactType: npm package. Documentation: https://1dsdocs.azurewebsites.net/getting-started/javascript-getting_started.html Language: typescript Platform: various Stackoverflow: N/A Tags: 1DSJSSDK ms.reviewedAt: 02/21/2019 ms.reviewedBy: ramthi

    Microsoft 1DS Web SDK Post Plugin


    1DS Web SDK Post Channel main functionality is to send data to OneCollector using POST, currently supporting XMLHttpRequest, fetch API and XDomainRequest.


    Package available here.

    Basic Usage


    import { AppInsightsCore, IExtendedConfiguration } from '@microsoft/1ds-core-js';
    import { PostChannel, IChannelConfiguration } from '@microsoft/1ds-post-js';
    var appInsightsCore: AppInsightsCore = new AppInsightsCore();
    var postChannel: PostChannel = new PostChannel();
    var coreConfig: IExtendedConfiguration = {
          instrumentationKey: "YOUR_TENANT_KEY",
          extensions: [
          extensionConfig: []
    var postChannelConfig: IChannelConfiguration = {
        eventsLimitInMem: 50
    coreConfig.extensionConfig[postChannel.identifier] = postChannelConfig;
    //Initialize SDK
    appInsightsCore.initialize(coreConfig, []);



    Config Description Type
    eventsLimitInMem The number of events that can be kept in memory before the SDK starts to drop events. By default, this is 10,000. number
    immediateEventLimit [Optional] Sets the maximum number of immediate latency events that will be cached in memory before the SDK starts to drop other immediate events only, does not drop normal and real time latency events as immediate events have their own internal queue. Under normal situations immediate events are scheduled to be sent in the next Javascript execution cycle, so the typically number of immediate events is small (~1), the only time more than one event may be present is when the channel is paused or immediate send is disabled (via manual transmit profile). By default max number of events is 500 and the default transmit time is 0ms. Added in v3.1.1 number
    autoFlushEventsLimit [Optional] If defined, once this number of events has been queued the system perform a flush() to send the queued events without waiting for the normal schedule timers. Default is undefined number
    httpXHROverride The HTTP override that should be used to send requests, request properties and headers should be added to the request to maintain correct functionality with other plugins. IXHROverride
    overrideInstrumentationKey Override for Instrumentation key. string
    overrideEndpointUrl Override for Endpoint where telemetry data is sent. string
    disableTelemetry The master off switch. Do not send any data if set to TRUE. boolean
    ignoreMc1Ms0CookieProcessing MC1 and MSFPC cookies will not be provided. Default is false. boolean
    payloadPreprocessor POST channel preprocessing function. Can be used to gzip the payload (and set appropriate HTTP headers) before transmission. Function
    payloadListener POST channel function hook to listen to events being sent, called after the batched events have been committed to be sent. Also used by Remote DDV Channel to send requests. Function
    disableEventTimings [Optional] By default additional timing metrics details are added to each event after they are sent to allow you to review how long it took to create serialized request. As not all users require this level of detail and it's now possible to get the same metrics via the IPerfManager and IPerfEvent, so you can now disabled this previous level. Default value is false to retain the previous behavior, if you are not using these metrics and performance is a concern then it is recommended to set this value to true. boolean
    valueSanitizer [Optional] The value sanitizer to use while constructing the envelope, if not provided the default sanitizeProperty() method is called to validate and convert the fields for serialization. The path / fields names are based on the format of the envelope (serialized object) as defined via the Common Schema 4.0 specification. IValueSanitizer
    stringifyObjects [Optional] During serialization, when an object is identified should the object serialized by true => JSON.stringify(theObject); otherwise theObject.toString(). Defaults to false. boolean
    enableCompoundKey [Optional] Enables support for objects with compound keys which indirectly represent an object eg. event: { "somedata.embeddedvalue": 123 } where the "key" of the object contains a "." as part of it's name. Defaults to false. boolean
    disableOptimizeObj [Optional] Switch to disable the v8 optimizeObject() calls used to provide better serialization performance. Defaults to false. boolean


    Config Description Type
    sendPOST This method sends data to the specified URI using a POST request. If sync is true then the request is sent synchronously. The oncomplete function should always be called after the request is completed (either successfully or timed out or failed due to errors). function

    Payload Preprocessors

    interface IPayloadData {
        urlString: string;
        data: Uint8Array | string;
        headers?: { [name: string]: string };
    type PayloadPreprocessorFunction = (payload: IPayloadData, callback: (modifiedBuffer: IPayloadData) => void) => void;

    To perform some preprocessing operation on your payload before it is sent over the wire, you can supply the POST channel config with a payloadPreprocessor function. A typical usage of it would be to gzip your payloads.

    const zlib = require('zlib');
    const gzipFn: PayloadPreprocessorFunction = (payload: IPayloadData, cb) => {
      zlib.gzip(payload.data, (err, dataToSend) => {
        if (err) return cb(payload); // send original payload on error
        const payloadToSend = {
          headers: { ...payload.headers, 'Content-Encoding': 'gzip' };
          data: dataToSend,

    XHR Override sample using node.js Https module

    const oneDs = require('@microsoft/1ds-analytics-js');
    const https = require('https');
    // XHR override using node.js https module
    var customHttpXHROverride= {
      sendPOST: (payload, oncomplete) => {
        var options = {
          method: 'POST',
          headers: {
            "Content-Type": "application/json",
            "Content-Length": Buffer.byteLength(payload.data)
        const req = https.request(payload.urlString, options, res => {
          res.on('data', function (responseData) {
            oncomplete(res.statusCode, res.headers, responseData.toString());
    var postChannelConfig = {
        httpXHROverride: customHttpXHROverride

    IValueSanitizer Paths / Fields which are excluded

    To ensure that the service can continue to accept events that are sent from the SDK, some paths and fields are explicitly blocked and are never processed via any configured valueSanitizer. These fields are blocked at the serialization level and cannot be overridden.

    The path / fields names are based on the format of the envelope (serialized object) as defined via the Common Schema 4.0 specification, so the path / field names used for the IValueSanitizer are based on how the data is serialized to the service (CS 4.0 location) and not specifically the location on the event object you pass into the track methods (unless they are the same).

    The currently configured set of fields include

    Excluded Part A fields

    • All direct top-level fields of the envelope, this includes "ver"; "name"; "time" and "iKey". see Common Schema 4.0 - Part A for all defined fields. Note: This exclusion does does not match sub-keys (objects) like "ext", "data" and "properties".
    • All fields of the web extension, this includes all fields and sub keys of "ext.web" (example fields include "ext.web.browser"; "ext.web.domain"; "ext.web.consentDetails"). see Common Schema 4.0 - Part A Extension - web for the complete set of defined fields.
    • All fields and paths of the metadata extension, this includes all fields and sub keys of "ext.metadata". see Common Schema 4.0 - Part A Extension - metadata for the complete set of defined fields.

    Synchronous Events

    By default events are batched and sent asynchronously, there are times when you want to send events immediately during the same JavaScript execution cycle.

    To support this you can set the sync property on an event to tell the PostChannel to skip the normal event batching and send this event now within it's own outbound connection. Because each sync event will cause a new request / connection (per event) you should use this approach SPARINGLY to avoid creating an excessive number of requests from the users browser which may have a negative impact on their experience.

    Note: If the initial synchronous request fails (not the normal case) any sync event will be queued for resending as an asynchronous batch (unless an "unload" event has been detected).

    Supported Sync values

    Supported event sync values to cause an event to be sent immediately during the same JavaScript execution cycle.

    In the case of the sendBeacon() and fetch() [with keepalive] (SyncFetch) both of these API's have a maximum payload size defined as 64Kb, as such if the size of the serialized (JSON) events are larger than this the events will be dropped as there is no safe way to send the event.

    Name Value Description
    Batched undefined,
    This is the default situation and will cause the event to be Batched and sent asynchronously.
    Synchronous true,
    Attempt to send the request using the default synchronous method.
    This will use the first available transport option:
    - httpXHROverride;
    -XMLHttpRequest (with sync flag);
    -fetch() [with keepalive] (Since v3.1.3);
    -sendBeacon() (Since v3.1.3)
    SendBeacon 2 (Since v3.1.3) Attempt to send the event synchronously with a preference for the sendBeacon() API.
    This will use the first available transport option:
    -fetch() [with keepalive];
    -XMLHttpRequest (with sync flag);
    SyncFetch 3 (Since v3.1.3) Attempt to send the event synchronously with a preference for the fetch() API with the keepalive flag, the SDK checks to ensure that the fetch() implementation supports the 'keepalive' flag and if not it will skip this transport option.
    This will use the first available transport option:
    -fetch() [with keepalive];
    -XMLHttpRequest (with sync flag);

    The named values are available in TypeScript via the EventSendType const enum class since v3.1.3.

    Note: The SDK explicitly checks for keepalive support for fetch() via the Request class, so if not available this transport will not be used. Browsers natively supporting fetch() keepalive, as such any polyfill would also need to support this flag for it to be used.

    Special sendBeacon() Note

    As the sendBeacon() API does not provide any response handling, any events sent via this method are considered to have been successfully sent, even if the browser fails to send the requests. The only exception is that if the browser returns false indicating that it can't accept the sendBeacon() request, in this case the SDK will send a dropped event notification.

    When to use 'sync' events

    Events that cause a page navigation can cause a race condition that could result in either event loss or duplication. This happens when any previously batched events have been sent (the request is in-flight) and the browser subsequently cancels the request before a response is processed AND it also triggers the JavaScript "cancel" or "abort" event, normally only during the unload process.

    The SDK listens to all supported "unload" events (unload, beforeunload and pagehide) and when any one of these are detected it will immediately send all (unsent) batched events via the "SendBeacon" (and fallback) methods above. This successfully mitigates the event loss case above, but it can compound the event duplication case for some scenarios as the SDK works to ensure that all events are sent and acknowledged.

    This situation has become more prevalent with the enforcement by modern browsers to disallow, cancel or abort the usage of synchronous Xhr requests during page "unload" event.

    There are effectively 2 scenarios where you should consider adding the sync property to an event (using the asynchronous SendBeacon and SyncFetch values) to remove the possibility of event duplication (the WebAnalytics extension already handles these cases).

    1. You want to send your own event during the page "unload" events and you have hooked the "unload" events yourself (before) initializing the SDK.
    • When you listen to the events "before" the SDK initializes, there is a small window of time where any "batched" event may get sent (and therefore become in-flight) before the SDK receives and processes the "unload" events, thus the potential race condition.
    • If you attach to the "unload" events "after" the SDK is initialized, it will now (since v3.1.3) automatically convert all received event(s) into "sync" (SendBeacon) events to ensure delivery.
    1. You want to send you own telemetry event(s) based on some user action after which a page-navigation immediately occurs, either via an anchor <a /> containing a href and letting the event bubble or by directly causing a navigation via a form Post or location change.
    • This is because because the href / post / location change will eventually cause an "unload" event to occur and therefore (potentially) any outbound (in-flight) requests may get canceled and cause event to be duplicated.
    • While this situation can occur with any other batched events, it is more likely to occur when events are created during these know situations that are known to directly trigger the "unload" cycle.

    API documentation


    Sample App

    React sample App.

    React Native sample App.

    Learn More

    You can learn more in 1DS First party getting started.

    Data Collection

    The software may collect information about you and your use of the software and send it to Microsoft. Microsoft may use this information to provide services and improve our products and services. You may turn off the telemetry as described in the repository. There are also some features in the software that may enable you and Microsoft to collect data from users of your applications. If you use these features, you must comply with applicable law, including providing appropriate notices to users of your applications together with a copy of Microsoft's privacy statement. Our privacy statement is located at https://go.microsoft.com/fwlink/?LinkID=824704. You can learn more about data collection and use in the help documentation and our privacy statement. Your use of the software operates as your consent to these practices.

    To turn off sending telemetry to Microsoft, ensure that the POST channel is not configured in the extensions. See below configuration for example:

    var coreConfig: IExtendedConfiguration = {
          instrumentationKey: "YOUR_TENANT_KEY",
          extensions: [
          extensionConfig: []




    npm i @microsoft/1ds-post-js

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