◈ Code Lab is in development. New lessons and improvements are on the way. Progress can be deleted.

JAVASCRIPT / CHAPTER 05

JavaScript
Forms.

Forms in JavaScript: labels, reading fields, checkbox/radio, FormData, empty vs zero, HTML constraints, the Constraint API, aria errors, and a simulated signup. Client validation helps, but the server re-checks. Learn and Practice; challenges are separate.

Choose a section

LearnPracticeChallenges

Lesson with explanation and a guided task. Theory stays readable; completion requires a passing solution.

Challenges are optional and do not block the next chapter.

Start lesson Random task

JavaScript

10 lessons available

Learn0/10

Practice0/10

Challenges0/3

The foundations behind your ideas.

1. 01

   Labels & Fields · Locked

   label for / input id

   Open lesson
2. 02

   Read Controls · Locked

   value of text, number, select

   Open lesson
3. 03

   Checkbox & Radio · Locked

   value vs checked

   Open lesson
4. 04

   FormData · Locked

   FormData and name

   Open lesson
5. 05

   Normalize & Zero · Locked

   trim, Number, empty vs 0

   Open lesson
6. 06

   HTML Constraints · Locked

   required, type, min/max, pattern

   Open lesson
7. 07

   Constraint API · Locked

   setCustomValidity and clearing

   Open lesson
8. 08

   Aria Errors · Locked

   aria-invalid and aria-describedby

   Open lesson
9. 09

   Submit & Reset · Locked

   preventDefault, success, reset()

   Open lesson
10. 10

    Signup Project · Locked

    multi-field form with validation

    Open lesson