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    1.1.4 • Public • Published


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    A code library for implementing frontend browser logging and exception capturing in LogDNA. Capture browser errors and log messages from your console and centralize them to your LogDNA instance. Optionally, use the LogDNA Browser Logger Template to get out-of-the-box Views, Boards, and Screens to analyze your browser logs.

    Module Installation

    Browser Logger is in Beta - API will evolve as we continue to develop and refine new features.

    Using NPM:

    npm install @logdna/browser

    Using Yarn:

    yarn add @logdna/browser

    Example Usage

    ⚠️ Before logs can be sent to LogDNA you must add your web application URL to your LogDNA account CORS configuration.

    import logdna from '@logdna/browser';
    // Found in Settings > Organization > API Keys
    const LOGDNA_INGESTION_KEY = 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx';
      // Context is appended to the metadata of each message sent to LogDNA
      // Add any custom meta data such as:
      version: 'v1.0.2',
      sessionReplay: 'http://mySessionReplayTool/',
      user: {
        email: '',
        userId: '987654321',
    logdna.log('Hello world!');
    // By default captures console messages (see `console` options below).
    console.log('Hello world!');

    Enable CORS in LogDNA

    ⚠️ Before logs can be sent to LogDNA you must add your web application URL to your LogDNA account CORS configuration.

    • Login to LogDNA
    • Go to Settings
    • Click on Organizations
    • Click on Whitelist Domains
      • Add your web application's full URL, including the https and any port information
      • Note: This may take around 15 minutes before the domain is properly whitelisted.
      • ex:
      • ex: http://localhost:3000

    Browser Logger Template

    Use the LogDNA Browser Logger Template to get out-of-the-box Views, Boards, and Screens to analyze your errors and log messages from Browser Logger.

    Example Board included in the Template:

    Example screenshot of Browser Logger Template

    Send log lines to LogDNA

    There are two ways to send log lines to LogDNA:

    1. Using the console.[log, error, warn, debug, info] with the configuration option console: true will send console messages to LogDNA and also to the browser's devtools console
    2. Using one of the following methods will just send the log message to LogDNA without sending the information to the console (unless debug is set to true in the configuration options). The log parameter message can be of any type.
    import logdna from '@logdna/browser';
    logdna.log('My log message');
    logdna.error('My error message');
    logdna.debug('My debug message');'My info message');
    logdna.warn('My warn message');

    Each method accepts an additional lineContext parameter to add additional metadata to the meta log field in LogDNA


    logdna.log('My log message', {
      thing: 'Extra Metadata',

    Add custom metadata for log lines

    Use the logdna.addContext({ }) method any time after initialization to add any custom metadata to each log line. This is useful to send application version information, logged-in user or account information, links to additional tools such as session replays, and just about anything else that you want associated with each log line.

      // Add any custom metadata such as:
      version: 'v1.0.2',
      sessionReplay: 'http://mySessionReplayTool/',
      user: {
        email: '',

    LogDNA's Browser Logger will automatically add the user's browser information and the window.location object to the log line.

    Example of automatically added context:

    "sessionId": "d1b69ea3-41c4-4b9b-85e2-32fb94cb219c",
    "browser": {
      "name": "chrome",
      "version": "87.0.4280",
      "os": "Mac OS",
      "type": "browser"
    "location": {
      "ancestorOrigins": {},
      "href": "https://your-web-app/home?q=1234567890",
      "origin": "https://your-web-app",
      "protocol": "https:",
      "host": "your-web-app",
      "hostname": "your-web-app",
      "port": "",
      "pathname": "/home",
      "search": "?q=1234567890",
      "hash": ""

    Session ID

    When LogDNA's Browser Logger is initialized it will generate a unique uuid v4 sessionId. This sessionId will make it easy to follow a particular user/session within the LogDNA console.

    Defining a Custom Session ID

    You can set a custom session sessionId by calling logdna.setSessionId('your-custom-id'). Log lines sent before setting a custom session ID may contain the previous auto generated session ID.

    Configuration Options

    Example Configuration:

    logdna.init(LOGDNA_INGESTION_KEY, {
      app: 'my-app',
      console: {
        integrations: ['error', 'warn'],
      sampleRate: 5,
    options default value type description
    app window.location.hostname string Name of your application
    env string An environment label attached to each message (ex. production, staging)
    hostname logdna-browser-logger string A hostname associated with each log line, populates the Source field in the LogDNA UI.
    tags 'LogDNA-Browser' string or string[] Add custom tags used in the LogDNA log line interface. Will always contain LogDNA-Browser.
    enableStacktrace true boolean Enable adding stack traces for each log message (does not affect error stack traces)
    console true boolean or object Enable sending console message to LogDNA for all supported methods or an options object
    console.enable false boolean Enable sending console message to LogDNA
    console.integrations ['log', 'info', 'debug', 'warn', 'error'] array Console methods to override for sending logs to LogDNA and to the console
    globalErrorHandlers true boolean or object Enable adding a global error handler and unhandledPromiseRejection handler to forward to LogDNA
    globalErrorHandlers.enableErrorHandler false boolean Enable automatic capturing and logging of unhandled errors.
    globalErrorHandlers.enableUnhandledPromiseRejection false boolean Enable automatic capturing and logging of unhandled promised rejections.
    sampleRate 100 number Percentage of sessions to track from 0 to 100. 0 for none 100 for all
    url string LogDNA ingestion URL
    debug false boolean When debug is true, logdna.<log, error, warn, info, debug> methods will log to both LogDNA and to the console. When false these methods will only send to LogDNA. Note: Logging console message to LogDNA is also dependant the enabled console integrations
    flushInterval 250 number Number of milliseconds to buffer log lines before sending to LogDNA
    disabled false boolean Disable the logger from sending logs

    sampleRate option

    You can decrease the percentages of sessions that send logs to LogDNA by specifying the sampleRate option. The sampleRate should be a number 0 to 100 which represents the percentage of sessions that you want to send logs to LogDNA. 0 mean no sessions will send logs, 100 (the default) means every session will have logs sent. 5 for example, means that just 5 percent of the client instances initialized will send logs.


    LogDNA's Browser Logger will buffer log message going to LogDNA, the default buffer time is 250ms and is customizable via the flushInterval configuration option.

    Unloading websites

    The LogDNA Browser Logger will attempt to flush the logs before the page unloads. This is done via the keepalive fetch requests flag. There is a 64kb internal fetch quota limit for keep-alive requests. Any request over that will result in a network error message as per the fetch spec.


    If there are failures when sending log lines to LogDNA the logger will attempt to retry sending the logs up to 30 times.

    Debug helpers

    The LogDNA Browser Logger exposes several helpers methods off the window.__LogDNA__ namespace.

    Show the current configuration


    Show the current context


    Turn debugging on and off. This is helpful for when logging all of your messages via the logdna log methods in prod but would like to see then in the browser console while debugging.


    Project Examples

    Project examples can be found under /examples.

    React Example

    npm link
    cd examples/react-example
    npm install
    npm link "@logdna/browser"

    Visit http://localhost:3000

    HTML Example

    npm run build
    npm run serve # Starts up static server for build on localhost:5000
    cd examples/html-example
    npm install
    npm start

    Visit http://localhost:1234

    Happy Logging!


    npm i @logdna/browser

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