Svelte

Prerequisites

• You need a Sentry account and project

Features

In addition to capturing errors, you can monitor interactions between multiple services or applications by enabling tracing. You can also get to the root of an error or performance issue faster, by watching a video-like reproduction of a user session with session replay.

Select which Sentry features you'd like to install in addition to Error Monitoring to get the corresponding installation and configuration instructions below.

Install

Sentry captures data by using an SDK within your application’s runtime.

npm install @sentry/svelte --save

Configure

Configuration should happen as early as possible in your application's lifecycle.

To use the SDK, initialize it in your Svelte entry point before bootstrapping your app. In a typical Svelte project, that is your main.js or main.ts file.

import "./app.css";
import App from "./App.svelte";

import * as Sentry from "@sentry/svelte";

// Initialize the Sentry SDK here
Sentry.init({
  dsn: "https://examplePublicKey@o0.ingest.sentry.io/0",
  integrations: [
    Sentry.browserTracingIntegration(),
    Sentry.replayIntegration(),
  ],

  // Set tracesSampleRate to 1.0 to capture 100%
  // of transactions for tracing.
  // We recommend adjusting this value in production
  // Learn more at
  // https://docs.sentry.io/platforms/javascript/configuration/options/#traces-sample-rate
  tracesSampleRate: 1.0,

  // Set `tracePropagationTargets` to control for which URLs trace propagation should be enabled
  tracePropagationTargets: ["localhost", /^https:\/\/yourserver\.io\/api/],

  // Capture Replay for 10% of all sessions,
  // plus 100% of sessions with an error
  // Learn more at
  // https://docs.sentry.io/platforms/javascript/session-replay/configuration/#general-integration-configuration
  replaysSessionSampleRate: 0.1,
  replaysOnErrorSampleRate: 1.0,
});

const app = new App({
  target: document.getElementById("app"),
});

export default app;

Once you've done this, the SDK will automatically capture unhandled errors and promise rejections, and monitor performance in the client. You can also manually capture errors.

Add Readable Stack Traces to Errors

Depending on how you've set up your project, the stack traces in your Sentry errors probably won't look like your actual code.

To fix this, upload your source maps to Sentry. The easiest way to do this is by using the Sentry Wizard:

npx @sentry/wizard@latest -i sourcemaps

The wizard will guide you through the following steps:

• Logging into Sentry and selecting a project
• Installing the necessary Sentry packages
• Configuring your build tool to generate and upload source maps
• Configuring your CI to upload source maps

For more information on source maps or for more options to upload them, head over to our Source Maps documentation.

Verify

This snippet includes an intentional error, so you can test that everything is working as soon as you set it up.

<button
  type="button"
  on:click={() => {
    throw new Error("Sentry Frontend Error");
  }}
>
  Throw error
</button>;

This snippet adds a button that throws an error in a Svelte component.

To view and resolve the recorded error, log into sentry.io and select your project. Clicking on the error's title will open a page where you can see detailed information and mark it as resolved.