Testing is the process of checking whether your code works as expected.
In real-world development, writing code is only half the job.
The other half is making sure that the code keeps working even when changes are made.
Professional developers use testing to:
- Find bugs early
- Avoid breaking existing features
- Improve confidence in their code
- Deliver high-quality software
Learning testing from the beginning helps students become reliable and job-ready developers.
Why Testing is Important
- Detects errors before users do
- Saves time in debugging later
- Makes code safer to change
- Improves software quality
- Builds trust in applications
Without testing, even small changes can create big problems.
The function works for numbers but gives a wrong result when a string is passed.
Without testing, this bug may go unnoticed.
Here, we manually check different inputs and outputs.
This is called manual testing — the simplest form of testing.
These examples show why testing is important in real development.
By understanding testing early, students gain the mindset of professional developers who care about quality, reliability, and long-term success of their JavaScript applications.