Development · Intermediate
TypeScript for impossible states
An interface state model that replaces contradictory flags with explicit alternatives. Practise TypeScript narrowing, validate incoming data and keep selections consistent as the underlying collection changes.
Written by Akis Apostoliadis for Skillfolio · 4 written lessons · Self-paced
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Course price: $79 USD, plus applicable tax. One payment for this course. Compare all-course package prices: $29/month or $299 lifetime.
What you’ll make
A typed resource-loading model with exhaustive rendering and validated external input.
Before you begin
JavaScript objects, functions and promises; basic TypeScript syntax.
Who it’s for
JavaScript developers learning to model interface data with TypeScript.
- Discriminated unions
- Narrowing
- Boundary validation
The complete curriculum
Preview the first lesson free. Purchase unlocks the remaining lessons, project and downloads.
Replace combinations with named states
Replace contradictory loading flags with a discriminated union.
14 min read · 45 min practice · Free preview
Let narrowing guide the renderer
Use narrowing and exhaustiveness to keep rendering aligned with the state model.
17 min read · 60 min practice · Included with purchase
Treat outside data as unknown
Validate unknown external values before introducing them into trusted application state.
15 min read · 45 min practice · Included with purchase
Keep selection consistent with the collection
Reconcile selection whenever the authoritative collection changes.
17 min read · 75 min practice · Included with purchase
See the work
Make missing states visible. Completed instructor specimen using fictional teaching material; not a learner result.This course works towards: A typed resource-loading model with exhaustive rendering and validated external input.
Explore completed teaching examples and the decisions behind them. These are instructor-authored examples, not learner testimonials.
What’s included
- Original written lessons, worked examples and guided practice.
- A course project, review criteria and reference responses.
- Downloadable course materials for purchased lessons.
Explore the course before committing. Start with the free lesson, or compare other courses.