Trade-offs; Ref Patterns; Default Values
Compare controlled vs uncontrolled inputs, use refs for reads, and provide sensible defaults.
Trade-offs; Ref Patterns; Default Values is a free React Academy lesson on CoddyKit — lesson 1 of 2. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the React Academy learning path, one of 2 lessons in the course, and your progress syncs across the web and the CoddyKit app.
Controlled vs uncontrolled
Goal: Pick the right input style.
- Controlled: value in state; re-render on change
- Uncontrolled: DOM keeps value; read via ref on demand
- Defaults: defaultValue, defaultChecked
Trade-offs at a glance
- Controlled: great for live validation, masks, syncing other fields
- Uncontrolled: fewer renders; simple submit-only forms
- Mix: controlled for key fields, uncontrolled for optional ones
Demo: controlled input
A controlled field stores value in state and updates on every change.
<div id="root"></div>
Demo: uncontrolled with ref
An uncontrolled field uses the DOM's value; we read it with a ref when needed.
<div id="root"></div>
Defaults & when to control
Use defaultValue/defaultChecked for uncontrolled defaults; switch to controlled when you need live rules.
<div id="root"></div>
Tips & pitfalls
- Do not mix value and defaultValue on the same input
- Use refs to read uncontrolled values
- Pick controlled when UI reacts to each keystroke
Controlled vs uncontrolled check
Recap
Recap: Controlled for live rules and derived state; uncontrolled for simple submit-only reads. Use ref to read values and defaultValue for initial content.
Frequently asked questions
Is the “Trade-offs; Ref Patterns; Default Values” lesson free?
Yes — the full text of “Trade-offs; Ref Patterns; Default Values” is free to read here on the web, and the React Academy course includes 2 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the React Academy course, upgrade to CoddyKit PRO.
What will I learn in “Trade-offs; Ref Patterns; Default Values”?
Compare controlled vs uncontrolled inputs, use refs for reads, and provide sensible defaults. You practise React Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start React Academy?
No prior experience is required. React Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 1 of 2, so you can start here or from the beginning and move at your own pace.
How long does the “Trade-offs; Ref Patterns; Default Values” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this React Academy lesson?
Yes. Every React Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Trade-offs; Ref Patterns; Default Values
- Prop Getters & State Reducer (Light)