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Microsoft Application Insights SDK for JavaScript
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Application Insights JavaScript SDK

Build Status Build Status npm version minified size size gzip size

Note: The documentation for applicationinsights-js has moved here. If you are looking to upgrade to the new version of the SDK, please see the Upgrade Guide.

Getting Started

  1. Create an Application Insights resource in Azure by following these instructions.
  2. Grab the Instrumentation Key (aka "ikey") from the resource you created in step 1. Later, you'll add it to the instrumentationKey setting of the Application Insights JavaScript SDK.
  3. Add Application Insights to your app. There are 2 ways to do this.

Basic Usage

NPM Setup (ignore if using Snippet Setup)

import { ApplicationInsights } from '@microsoft/applicationinsights-web'

const appInsights = new ApplicationInsights({ config: {
  /* ...Other Configuration Options... */
} });

Snippet Setup (Ignore if using NPM Setup)

If your app does not use NPM, you can directly instrument your webpages with Application Insights by pasting this snippet at the top of each your pages. Preferably, it should be the first script in your <head> section so that it can monitor any potential issues with all of your dependencies.

<script type="text/javascript">
var sdkInstance="appInsightsSDK";window[sdkInstance]="appInsights";var aiName=window[sdkInstance],aisdk=window[aiName]||function(e){function n(e){t[e]=function(){var n=arguments;t.queue.push(function(){t[e].apply(t,n)})}}var t={config:e};t.initialize=!0;var i=document,a=window;setTimeout(function(){var n=i.createElement("script");n.src=e.url||"",i.getElementsByTagName("script")[0].parentNode.appendChild(n)});try{t.cookie=i.cookie}catch(e){}t.queue=[],t.version=2;for(var r=["Event","PageView","Exception","Trace","DependencyData","Metric","PageViewPerformance"];r.length;)n("track"+r.pop());n("startTrackPage"),n("stopTrackPage");var s="Track"+r[0];if(n("start"+s),n("stop"+s),n("setAuthenticatedUserContext"),n("clearAuthenticatedUserContext"),n("flush"),!(!0===e.disableExceptionTracking||e.extensionConfig&&e.extensionConfig.ApplicationInsightsAnalytics&&!0===e.extensionConfig.ApplicationInsightsAnalytics.disableExceptionTracking)){n("_"+(r="onerror"));var o=a[r];a[r]=function(e,n,i,a,s){var c=o&&o(e,n,i,a,s);return!0!==c&&t["_"+r]({message:e,url:n,lineNumber:i,columnNumber:a,error:s}),c},e.autoExceptionInstrumented=!0}return t}(

Sending Telemetry to the Azure Portal

If initialized using the snippet, your Application Insights instance is located by default at window.appInsights

appInsights.trackEvent({name: 'some event'});
appInsights.trackPageView({name: 'some page'});
appInsights.trackPageViewPerformance({name : 'some page', url: 'some url'});
appInsights.trackException({exception: new Error('some error')});
appInsights.trackTrace({message: 'some trace'});
appInsights.trackMetric({name: 'some metric', average: 42});
appInsights.trackDependencyData({absoluteUrl: 'some url', responseCode: 200, method: 'GET', id: 'some id'});
appInsights.stopTrackPage("pageName", {customProp1: "some value"});
appInsights.stopTrackEvent("event", {customProp1: "some value"});

Setting Up Autocollection

All autocollection is on by default. By using the full version of the JavaScript Application Insights SDK, we collect for you

  • Uncaught exceptions in your app, including information on
    • Stack trace
    • Exception details and message accompanying the error
    • Line & column number of error
    • URL where error was raised
  • Network Dependency Requests made by your app XHR and Fetch (fetch collection is disabled by default) requests, include information on
    • Url of dependency source
    • Command & Method used to request the dependency
    • Duration of the request
    • Result code and success status of the request
    • ID (if any) of user making the request
    • Correlation context (if any) where request is made
  • User information (e.g. Location, network, IP)
  • Device information (e.g. Browser, OS, version, language, resolution, model)
  • Session information

Telemetry Initializers

Telemetry initializers are used to modify the contents of collected telemetry before being sent from the user's browser. They can also be used to prevent certain telemetry from being sent, by returning false. Multiple telemetry initializers can be added to your Application Insights instance, and they are executed in order of adding them.

The input argument to addTelemetryInitializer is a callback that takes a ITelemetryItem as an argument and returns a boolean or void. If returning false, the telemetry item is not sent, else it proceeds to the next telemetry initializer, if any, or is sent to the telemetry collection endpoint.

An example of using telemetry initializers:

var telemetryInitializer = (envelope) => { = 'This item passed through my telemetry initializer';
appInsights.trackTrace({message: 'This message will use a telemetry initializer'});

appInsights.addTelemetryInitializer(() => false); // Nothing is sent after this is executed
appInsights.trackTrace({message: 'this message will not be sent'}); // Not sent


Most configuration fields are named such that they can be defaulted to falsey. All fields are optional except for instrumentationKey.

Name Default Description
instrumentationKey null Required
Instrumentation key that you obtained from the Azure Portal.
accountId null An optional account id, if your app groups users into accounts. No spaces, commas, semicolons, equals, or vertical bars
sessionRenewalMs 1800000 A session is logged if the user is inactive for this amount of time in milliseconds. Default is 30 minutes
sessionExpirationMs 86400000 A session is logged if it has continued for this amount of time in milliseconds. Default is 24 hours
maxBatchSizeInBytes 10000 Max size of telemetry batch. If a batch exceeds this limit, it is immediately sent and a new batch is started
maxBatchInterval 15000 How long to batch telemetry for before sending (milliseconds)
disableExceptionTracking false If true, exceptions are no autocollected. Default is false.
disableTelemetry false If true, telemetry is not collected or sent. Default is false.
enableDebug false If true, internal debugging data is thrown as an exception instead of being logged, regardless of SDK logging settings. Default is false.
Note: Enabling this setting will result in dropped telemetry whenever an internal error occurs. This can be useful for quickly identifying issues with your configuration or usage of the SDK. If you do not want to lose telemetry while debugging, consider using consoleLoggingLevel or telemetryLoggingLevel instead of enableDebug.
consoleLoggingLevel 0 Logs internal Application Insights errors to console.
0: off,
1: Critical errors only,
2: Everything (errors & warnings)
telemetryLoggingLevel 1 Sends internal Application Insights errors as telemetry.
0: off,
1: Critical errors only,
2: Everything (errors & warnings)
diagnosticLogInterval 10000 (internal) Polling interval (in ms) for internal logging queue
samplingPercentage 100 Percentage of events that will be sent. Default is 100, meaning all events are sent. Set this if you wish to preserve your datacap for large-scale applications.
autoTrackPageVisitTime false If true, on a pageview,the previous instrumented page's view time is tracked and sent as telemetry and a new timer is started for the current pageview. Default is false.
disableAjaxTracking false If true, Ajax calls are not autocollected. Default is false.
disableFetchTracking true If true, Fetch requests are not autocollected. Default is true
overridePageViewDuration false If true, default behavior of trackPageView is changed to record end of page view duration interval when trackPageView is called. If false and no custom duration is provided to trackPageView, the page view performance is calculated using the navigation timing API. Default is false.
maxAjaxCallsPerView 500 Default 500 - controls how many ajax calls will be monitored per page view. Set to -1 to monitor all (unlimited) ajax calls on the page.
disableDataLossAnalysis true If false, internal telemetry sender buffers will be checked at startup for items not yet sent.
disableCorrelationHeaders false If false, the SDK will add two headers ('Request-Id' and 'Request-Context') to all dependency requests to correlate them with corresponding requests on the server side. Default is false.
correlationHeaderExcludedDomains Disable correlation headers for specific domains
correlationHeaderDomains Enable correlation headers for specific domains
disableFlushOnBeforeUnload false Default false. If true, flush method will not be called when onBeforeUnload event triggers
enableSessionStorageBuffer true Default true. If true, the buffer with all unsent telemetry is stored in session storage. The buffer is restored on page load
isCookieUseDisabled false Default false. If true, the SDK will not store or read any data from cookies.
cookieDomain null Custom cookie domain. This is helpful if you want to share Application Insights cookies across subdomains.
isRetryDisabled false Default false. If false, retry on 206 (partial success), 408 (timeout), 429 (too many requests), 500 (internal server error), 503 (service unavailable), and 0 (offline, only if detected)
isStorageUseDisabled false If true, the SDK will not store or read any data from local and session storage. Default is false.
isBeaconApiDisabled true If false, the SDK will send all telemetry using the Beacon API
sdkExtension null Sets the sdk extension name. Only alphabetic characters are allowed. The extension name is added as a prefix to the 'ai.internal.sdkVersion' tag (e.g. 'ext_javascript:2.0.0'). Default is null.
isBrowserLinkTrackingEnabled false Default is false. If true, the SDK will track all Browser Link requests.
appId null AppId is used for the correlation between AJAX dependencies happening on the client-side with the server-side requests. When Beacon API is enabled, it cannot be used automatically, but can be set manually in the configuration. Default is null
enableCorsCorrelation false If true, the SDK will add two headers ('Request-Id' and 'Request-Context') to all CORS requests tocorrelate outgoing AJAX dependencies with corresponding requests on the server side. Default is false
namePrefix undefined An optional value that will be used as name postfix for localStorage and cookie name.

Single Page Applications

By default, this SDK will not handle state based route changing that occurs in single page applications unless you use a plugin designed for your frontend framework (Angular, React, Vue, etc). Currently, we support a separate React plugin which you can initialize with this SDK and it will accomplish this for you in your React application. Otherwise, you must manually trigger pageviews on each route change. An example of accomplishing this for a React application is located here. Note that you must refresh the current operation's id as well as trigger an additional pageview: React Router history listener example

this.unlisten = this.props.history.listen((location, action) => { = Util.newId();
  ai.trackPageView({name: window.location.pathname});


For runnable examples, see Application Insights Javascript SDK Samples

Application Insights Web Basic

For a lightweight experience, you can instead install the basic version of Application Insights

npm i --save @microsoft/applicationinsights-web-basic

This version comes with the bare minimum amount of features and functionalities and relies on you to build it up as you see fit. For example, it performs no auto-collection (uncaught exceptions, ajax, etc). The APIs to send certain telemetry types, like trackTrace, trackException, etc, are not included in this version, so you will need to provide your own wrapper. The only api that is available is track. A sample is located here.

Available extensions for the SDK

React Native

Upgrading from the old Version of Application Insights

Breaking changes in the SDK V2 version:

  • To allow for better API signatures, some of the apis such as trackPageView, trackException have been updated. Running in IE8 or lower versions of the browser is not supported.
  • Telemetry envelope has field name and structure changes due to data schema updates.
  • Moved context.operation to context.telemetryTrace. Some fields were also changed ( --> telemetryTrace.traceID)
    • If you want to maunally refresh the current pageview id (e.g. in SPA apps) this can be done with = Util.newId()

If you are using the current application insights PRODUCTION SDK (1.0.20) and want to see if the new SDK works in runtime, please update URL depending on your current SDK loading scenario:

a) Download via CDN scenario: Update code snippet that you currently use to point to the following URL: ""

b) NPM scenario: Call downloadAndSetup to download full ApplicationInsights script from CDN and initialize it with instrumentation key.

    instrumentationKey: "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxx",
    url: ""

Test in internal environment to verify monitoring telemetry is working as expected. If all works, please update your api signatures appropriately to SDK V2 version and deploy in your production environments.

Build a new extension for the SDK

The beta SDK supports the ability to include multiple extensions at runtime. In order to create a new extension, please implement the following interface:


On initialization, config.extensions accepts an array of ITelemetryPlugin objects. These are hooked up and ITelemetryPlugin.processTelemetry() is chained based on priority of these plugins. Please note that higher the priority, the later your processing code will be invoked. The SDK supports a plugin model and channels can also be plugged in similarly (advanced scenario). Target scenarios for creating a brand new extension is to share a usage scenario that benefits multiple customers. Please follow guidelines

Here is the priority ranges available:

  • Regular extension priority can be between 201 to 499.
  • Priorty range < 201 is reserved.
  • Priority range > 1000 is for channels (advanced scenario)


const customPluginInstance = new YourCustomPlugin()
const appInsights = new ApplicationInsights({ config: {
	extensions: [customPluginInstance]
	// Other Configuration Options...

ITelemetryPlugin has a simpler base type IPlugin that you can instantiate for initialization purposes when SDK loads.

Build & Test this repo

  1. Install all dependencies
    npm install
  2. Build and test
    npm run build
    npm run test


At just 25 KB gzipped, and taking only ~15 ms to initialize, Application Insights adds a negligible amount of loadtime to your website. By using the snippet, minimal components of the library are quickly loaded. In the meantime, the full script is downloaded in the background.

While the script is downloading from the CDN, all tracking of your page is queued. Once the downloaded script finishes asynchronously initializing, all events that were queued are tracked. As a result, you will not lose any telemetry during the entire life cycle of your page. This setup process provides your page with a seamless analytics system, invisible to your users.


  • 25 KB gzipped
  • 15 ms overall initialization time
  • Zero tracking missed during life cycle of page

Browser Support

Chrome Firefox IE Opera Safari
Latest ✔ Latest ✔ 9+ ✔ Latest ✔ Latest ✔


We strongly welcome and encourage contributions to this project. Please read the contributor's guide located in the ApplicationInsights-Home repository. If making a large change we request that you open an issue first. We follow the Git Flow approach to branching.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact with any additional questions or comments.

Build together when changing multiple packages:

The vNext folder contains 8 packages that are components of this next version of the SDK. When making changes in multiple packages, you can build using the following commands in vNext folder:

  1. npm install -g @microsoft/rush

  2. rush rebuild --verbose This will build all packages in order of dependencies. If there are build errors, verbose options is required to view error details.

  3. rush test --verbose This will run tests in all packages in parallel.

If you are changing package versions or adding/removing any package dependencies, run> rush update --purge --recheck --full before building. Please check in any files that change under vNext\common\ folder.

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