Enhancing SvelteKitAuth with Custom Type Additions

Chapter 6 of Comprehensive Guide to SvelteKitAuth: Secure Authentication for SvelteKit Apps

Often, your IDE might complain that certain types are unrecognizable. This is common in SvelteKitAuth. To fix this, we need to add custom typings. Here is how we do it:

Step 1: Create a file named types/auth.d.ts at the same level as src. Here, we will extend the core Session type with our custom type.

import type { DefaultSession } from '@auth/core/types';

declare module '@auth/core/types' {
    interface Session {
        user: DefaultSession['user'] & Partial<IUser>;

interface IUser {
    name: string;
    email: string;
    image: string;
    picture: string;
    sub: string;
    access_token: string;
    id_token: string;
    scope: string;
    expires_in: number;
    token_type: string;
    expires_at: number;
    provider: string;
    type: string;
    providerAccountId: string;
    nickname: string;
    updated_at: string;
    email_verified: boolean;
    iss: string;
    aud: string;
    iat: number;
    exp: number;
    sid: string;
    jti: string;
    fav_num: string;

Step 2: Update the tsconfig.json file's types and include properties.

  "extends": "./.svelte-kit/tsconfig.json",
  "compilerOptions": {
    "types": ["vite/client", "svelte", "@auth/core", "@auth/sveltekit"]
  "include": [

Step 3: Restart your IDE.

In conclusion, enhancing SvelteKitAuth with custom type additions is a straightforward process that can significantly improve your development experience. By creating a custom typings file and updating your TypeScript configuration, you can ensure that your IDE recognizes all necessary types, reducing errors and improving code quality. Remember to restart your IDE after making these changes to apply the updates effectively. This small but crucial step can make a big difference in maintaining a smooth and efficient development workflow.

Here is the link to the GitHub repository with the codebase. In the next section, we will delve into initiating client-side sign-in and sign-out flows, further streamlining the user authentication journey.

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