Q52. How do you migrate a JavaScript project to TypeScript safely?
Migrate incrementally: establish a tsconfig, add TypeScript tooling, convert leaf modules first, define contracts at boundaries, enable strict checks progressively if needed, and run type checks in CI. Avoid replacing all uncertain values with any; track and reduce unsafe areas as the project evolves.
Start with modules that have few dependencies, add declarations for JavaScript libraries where needed, and make compiler errors visible rather than hiding them.
Note
Interview approach: define the concept, explain why it matters, then mention one trade-off or limitation.
TypeScript concept
// Illustrative TypeScript contract
type Identifier = string;
const id: Identifier = "item-1";💡 The example demonstrates the compile-time contract discussed in this question.
Key Takeaways
- Explain the concept in your own words.
- Know the practical trade-off and its limits.
- Use a small example to demonstrate the idea.
Knowledge Check
Which is a sound migration strategy?