@backtrace/browser

Backtrace Browser SDK

Backtrace captures and reports handled and unhandled exceptions in your production software so you can manage application quality through the complete product lifecycle.

The @backtrace/browser SDK connects your JavaScript application to Backtrace. The basic integration is quick and easy, after which you can explore the rich set of Backtrace features.

Table of Contents

1. Basic Integration - Reporting your first errors
   • Install the package
   • Integrate the SDK
   • Upload source maps
2. Error Reporting Features
   • Attributes
   • File Attachments
   • Breadcrumbs
   • Application Stability Metrics
     • Metrics Configuration
     • Metrics Usage
3. Advanced SDK Features
   • BacktraceClient options
   • Manually send an error
   • Modify/skip error reports
   • SDK Method Overrides

Basic Integration

Install the package

$ npm install @backtrace/browser

Integrate the SDK

Add the following code to your application before all other scripts to report client-side errors to Backtrace.

// Import the BacktraceClient from @backtrace/browser with your favorite package manager.
import { BacktraceClient, BacktraceConfiguration } from '@backtrace/browser';

// Configure client options
const options: BacktraceConfiguration = {
    // Name of the website/application
    name: 'MyWebPage',
    // Version of the website
    version: '1.2.3',
    // Submission url
    // <universe> is the subdomain of your Backtrace instance (<universe>.backtrace.io)
    // <token> can be found in Project Settings/Submission tokens
    url: 'https://submit.backtrace.io/<universe>/<token>/json',
};

// Initialize the client with the options
const client = BacktraceClient.initialize(options);

// By default, Backtrace will send an error for Uncaught Exceptions and Unhandled Promise Rejections

// Manually send an error
client.send(new Error('Something broke!'));

Upload source maps

Client-side error reports are based on minified code. Upload source maps and source code to resolve minified code to your original source identifiers.

(Source Map feature documentation)

Error Reporting Features

Attributes

Custom attributes are key-value pairs that can be added to your error reports. They are used in report aggregation, sorting and filtering, can provide better contextual data for an error, and much more. They are foundational to many of the advanced Backtrace features detailed in Error Reporting documentation.

There are several places where attributes can be added, modified or deleted.

Attach attributes object to BacktraceClient

It is possible to include an attributes object during BacktraceClient initialization. This list of attributes will be included with every error report, referred to as global attributes.

// Create an attributes object that can be modified throughout runtime
const attributes: Record<string, unknown> = {
    release: 'PROD',
};

// BacktraceClientOptions
const options: BacktraceConfiguration = {
    name: 'MyWebPage',
    version: '1.2.3',
    url: 'https://submit.backtrace.io/<universe>/<token>/json',

    // Attach the attributes object
    userAttributes: attributes,
};

// Initialize the client
const client = BacktraceClient.initialize(options);

You can also include attributes that will be resolved when creating a report:

// BacktraceClientOptions
const options: BacktraceConfiguration = {
    name: 'MyWebPage',
    version: '1.2.3',
    url: 'https://submit.backtrace.io/<universe>/<token>/json',

    // Attach the attributes object
    userAttributes: () => ({
        user: getCurrentUser(),
    }),
};

// Initialize the client
const client = BacktraceClient.initialize(options);

Add attributes during application runtime

Global attributes can be set during the runtime once specific data has be loaded (e.g. a user has logged in).

const client = BacktraceClient.initialize(options);
...

client.addAttribute({
    "clientID": "de6faf4d-d5b5-486c-9789-318f58a14476"
})

You can also add attributes that will be resolved when creating a report:

const client = BacktraceClient.initialize(options);
...

client.addAttribute(() => ({
    "clientID": resolveCurrentClientId()
}))

Add attributes to an error report

The attributes list of a BacktraceReport object can be directly modified.

const report: BacktraceReport = new BacktraceReport('My error message', { myReportKey: 'myValue' });
report.attributes['myReportKey'] = 'New value';

---

File Attachments

Files can be attached to error reports. This can be done when initalizing the BacktraceClient, updating the BacktraceClient, or dynamically for specific reports. When including attachments in BacktraceClient, all files will be uploaded with each report.

// Import attachment types from @backtrace/browser
import { BacktraceStringAttachment, BacktraceUint8ArrayAttachment  } from "@backtrace/browser";

// BacktraceStringAttachment should be used for text object like a log file, for example
const attachment1 = new BacktraceStringAttachment("logfile.txt", "This is the start of my log")

// BacktraceUint8ArrayAttachment should be used for binary files
const attachment2 = new BacktraceUint8ArrayAttachment("connection_buffer", new Uint8Array(2));

// Setup array of files to attach
const attachments = [attachment1];

// BacktraceClientOptions
const options = {
    name: "MyWebPage",
    version: "1.2.3",
    url: "https://submit.backtrace.io/<universe>/<token>/json",

    // Attach the files to all reports
    attachments,
}

const client = BacktraceClient.initialize(options);

// Later decide to add an attachment to all reports
client.addAttachment(attachment2)

// After catching an exception and generating a report
try {
    throw new Error("Caught exception!")
} catch (error) {
    const report = const report = new BacktraceReport(error, {}, [new BacktraceStringAttachment("CaughtErrorLog", "some error logging data here")])
    client.send(report);
}

---

Breadcrumbs

Breadcrumbs are snippets of chronological data tracing runtime events. This SDK records a number of events by default, and manual breadcrumbs can also be added.

(Breadcrumbs feature documentation)

Breadcrumbs Configuration

Option Name	Type	Description	Default	Required?
enable	Boolean	Determines if the breadcrumbs support is enabled. By default the value is set to true.	true	- [ ]
logLevel	BreadcrumbLogLevel	Specifies which log level severity to include. By default all logs are included.	All Logs	- [ ]
eventType	BreadcrumbType	Specifies which breadcrumb type to include. By default all types are included.	All Types	- [ ]
maximumBreadcrumbs	Number	Specifies maximum number of breadcrumbs stored by the library. By default, only 100 breadcrumbs will be stored.	100	- [ ]
intercept	(breadcrumb: RawBreadcrumb) => RawBreadcrumb | undefined;	Inspects breadcrumb and allows to modify it. If the undefined value is being returned from the method, no breadcrumb will be added to the breadcrumb storage.	All Breadcrumbs	- [ ]

import { BacktraceClient, BacktraceConfiguration } from '@backtrace/browser';

// BacktraceClientOptions
const options: BacktraceConfiguration = {
    // ignoring all but breadcrumbs config for simplicity
    breadcrumbs: {
        // breadcrumbs configuration
    },
};

// Initialize the client
const client = BacktraceClient.initialize(options);

Default Breadcrumbs

Type	Description
HTTP	Adds a breadcrumb with the url, request type, and reponse status for Fetch or XMLHttpRequests.
History	Adds breadcrumb on pushstate and popstate.
Document/Window	Adds a breadcrumb for document.click, document.dblclick, document.drag, document.drop, window.load, window.unload, window.pagehide, window.pageshow, window.online, and window.offline.
Console	Adds a breadcrumb every time console log is being used by the developer.

Intercepting Breadcrumbs

If PII or other information needs to be filtered from a breadcrumb, you can use the intercept function to skip or filter out the sensitive information. Any RawBreadcrumb returned will be used for the breadcrumb. If undefined is returned, no breadcrumb will be added.

Manual Breadcrumbs

In addition to all of the default breadcrumbs that are automatically collected, you can also manually add breadcrumbs of your own.

client.breadcrumbs?.info('This is a manual breadcrumb.', {
    customAttr: 'wow!',
});

---

Application Stability Metrics

The Backtrace Browser SDK has the ability to send usage Metrics to be viewable in the Backtrace UI.

(Stability Metrics feature documentation)

Metrics Configuration

Option Name	Type	Description	Default	Required?
metricsSubmissionUrl	String	Metrics server hostname. By default the value is set to https://events.backtrace.io.	https://events.backtrace.io	- [ ]
enable	Boolean	Determines if the metrics support is enabled. By default the value is set to true.	true	- [ ]
autoSendInterval	Number	Indicates how often crash free metrics are sent to Backtrace. The interval is a value in ms. By default, session events are sent on application startup/finish, and every 30 minutes while the application is running. If the value is set to 0. The auto send mode is disabled. In this situation the application needs to maintain send mode manually.	On application startup/finish	- [ ]
size	Number	Indicates how many events the metrics storage can store before auto submission.	50	- [ ]

Metrics Usage

// metrics will be undefined if not enabled
client.metrics?.send();

---

Advanced SDK Features

BacktraceClient

BacktraceClient is the main SDK class. Error monitoring starts when this singleton object is instantiated, and it will compose and send reports for unhandled errors and unhandled promise rejections. It can also be used to manually send reports from exceptions and rejection handlers. Do not create more than one instance of this object.

BacktraceClientOptions

The following options are available for the BacktraceClientOptions passed when initializing the BacktraceClient.

Option Name	Type	Description	Default	Required?
url	String	Submission URL to send errors to		- [x]
name	String	Your application name		- [x]
version	String	Your application version		- [x]
token	String	The submission token for error injestion. This is required only if submitting directly to a Backtrace URL. (uncommon)		- [ ]
userAttributes	Dictionary	Additional attributes that can be filtered and aggregated against in the Backtrace UI.		- [ ]
attachments	BacktraceAttachment[]	Additional files to be sent with error reports. See File Attachments		- [ ]
beforeSend	(data: BacktraceData) => BacktraceData | undefined	Triggers an event every time an exception in the managed environment occurs, which allows you to skip the report (by returning a null value) or to modify data that library collected before sending the report. You can use the BeforeSend event to extend attributes or JSON object data based on data the application has at the time of exception. See Modify/skip error reports)		- [ ]
skipReport	(report: BacktraceReport) => boolean	If you want to ignore specific types of error reports, we recommend that you use the skipReport callback. By using it, based on the data generated in the report, you can decide to filter the report, or send it to Backtrace.		- [ ]
captureUnhandledErrors	Boolean	Enable unhandled errors	true	- [ ]
captureUnhandledPromiseRejections	Boolean	Enable unhandled promise rejection	true	- [ ]
timeout	Integer	How long to wait in ms before timing out the connection	15000	- [ ]
ignoreSslCertificate	Boolean	Ignore SSL Certificate errors	false	- [ ]
rateLimit	Integer	Limits the number of reports the client will send per minute. If set to '0', there is no limit. If set to a value greater than '0' and the value is reached, the client will not send any reports until the next minute.	0	- [ ]
metrics	BacktraceMetricsOptions	See Backtrace Stability Metrics		- [ ]
breadcrumbs	BacktraceBreadcrumbsSettings	See Backtrace Breadcrumbs		- [ ]

Manually send an error

There are several ways to send an error to Backtrace:

// send as a string
await client.send('This is a string!');

// send as an Error
await client.send(new Error('This is an Error!'));

// as a BacktraceReport (string)
await client.send(new BacktraceReport('This is a report with a string!'));

// as a BacktraceReport (Error)
await client.send(new BacktraceReport(new Error('This is a report with a string!')));

Modify/skip error reports

A BeforeSend event is triggered when an exception in the managed environment occurs to which you can attach a handler. You can use the BeforeSend event to scrub PII, or extend attributes or JSON object data based on data your application has at the time of exception. A report can be skipped sompletely by returning a null value.

const client = BacktraceClient.initialize({
    url: SUBMISSION_URL,
    name: '@backtrace/browser-example',
    version: '0.0.1',
    beforeSend: (data: BacktraceData) => {
        // skip the report by returning a null from the callback
        if (!shouldSendReportToBacktrace(data)) {
            return undefined;
        }
        // apply custom attribute
        data.attributes['new-attribute"] = 'apply-data-in-callback';
        return data;
    },
});

SDK Method Overrides

BacktraceClient.builder is used to override default BacktraceClient methods. File and http operation overrides, for example, can be used to implement custom encryption for data at rest or in motion.

Do not use these operations to modify the data objects. See Modify/skip error reports for the correct method to modify a report before sending it to Backtrace.

const client = BacktraceClient.builder(options)
    .useRequestHandler(requestHandler)
    .useBreadcrumbSubscriber(breadcrumbSubscriber)
    .addAttributeProvider(attributeProvider)
    .build();