Handling JWT Token Expiration in Angular 17 — A Comprehensive Guide

Ayyaz Zafar
3 min readNov 20, 2023

Introduction

In this tutorial, we delve into a pivotal aspect of modern web applications: effectively managing JWT token expiration in Angular 17. Ensuring a secure and smooth user experience hinges on this critical functionality.

Deep Dive into JWT

JWT (JSON Web Token) is a URL-safe method for transmitting information, particularly used for authentication. It comprises three segments:

  • Header: Contains token type and algorithm.
  • Payload: Holds the claims or data.
  • Signature: Ensures the token’s integrity.

Before proceeding, verify your Angular version with ng version to ensure compatibility with Angular 17.

Starting with Angular

Create a new project using ng new [project-name].

Step-by-Step JWT Expiration Handling

Step 1: Setting Up JWT Decode

Install the JWT Decode package with:

npm install jwt-decode

This allows you to decode and inspect your JWT tokens.

Step 2: Creating an Interceptor

Generate a token interceptor using:

ng generate interceptor token

This interceptor will check for token expiration on each request.

Step 3: Registering the Interceptor

In app.config, register your interceptor:

import {provideHttpClient, withInterceptors} from "@angular/common/http";
import {tokenInterceptor} from "./token.interceptor";
....
providers: [
provideHttpClient(
withInterceptors(
[
tokenInterceptor
]
)
)
]

This integrates the interceptor with your Angular HTTP client.

Step 4: Implementing the Interceptor

In your interceptor, implement token expiration logic:

export const tokenInterceptor: HttpIntercepterfn=(reg, next){

const token =…

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