This Wednesday Wisdom deck dives deep into the essentials of Error Handling in Express with this insight into error types, custom handling techniques, and setup strategies to enhance your Express applications. Wednesday is a leading Product Engineering Agency. We have worked with over 50 Global Brands. Due to our product thinking expertise, Wednesday has been the agency of choice for fast-growing startups. Over 10% of India's Unicorns are our customers. We are known for our expertise in: 1. Data Engineering: Using DataOps principles, we build data pipelines that are cost-effective and performant and allow you to make strategic decisions. 2. Applied AI: We use large language models and your proprietary data to build data-centric intelligent apps for your customers. 3. App Development & Modernization: We use our expertise in strategy, product development & design to build web, mobile, TV & IoT Apps. We offer our expertise via the following services: - Launch: Idea from napkin sketch to product market fit. - Amplify: Engineering & design for companies with product market fit. - Control: Fast-paced, tight-deadline projects suited for enterprises. - Catalyse: Staff Augmentation If you want to explore an opportunity to work with Wednesday, send your resume to careers@wednesday.is.

1. Wednesday Wisdom
Error Handling in
Express
Presented by Vipin Chandra

2. Wednesday Wisdom
Contents
01
03
02
04
Need of it
Handling Custom Errors
How Error handling Work in express
Setting up Error handling in express
0 2 / 1 2

3. Wednesday Wisdom
Need.
0 3 / 1 2
Lead to Bad User
experience
Bad for
Business
Types of Error
Programming
Errors
Operational
Errors
Errors that developers
introduce into the code
Error that popup in user journey
Like invalid Paths , invalid user input ,
connection timeout

4. Wednesday Wisdom
How Error
Handling work
in express ?
0 4 / 1 2
Express Middleware functions
Default error Handler

5. Wednesday Wisdom
Middleware Functions?
0 5 / 1 2
Functions that came into play after server receives the
request and before the response fires to client
These functions have access to req and res object
We implement these functions for
Data processing
Querying
Api calls
Call other middleware

6. Wednesday Wisdom
Working ...
0 6 / 1 2
Triggered sequentially
Top to bottom

7. Wednesday Wisdom
Default Error handling
0 7 / 1 2
Express implicitly takes care of catching your errors to prevent your application
from crashing when it comes to error handling.
This is especially true for synchronous route handler code.
Default response to client

8. Wednesday Wisdom 0 8 / 1 2
asynchronous code
this will crash the server and no response will be send to the user
For handling errors raised during asynchronous code execution in Express, developers need to
themselves catch their errors and invoke the in-built error handler middleware using the next()
function.

9. Wednesday Wisdom 0 9 / 1 2
Example

10. Wednesday Wisdom 1 0 / 1 2
Handle Error in your own way
write error to log files
alert the user
redirect the user

11. Wednesday Wisdom 1 1 / 1 2
Setting up Error handling in
express

12. Thank
Thank
Thank
you!
you!
you!