TypeScript Course

See the full TypeScript path from first types to enterprise architecture, interviews, and runtime trust boundaries.

Define TypeScript as a compile-time contract language that emits JavaScript rather than a new runtime.

Explain the production problems TypeScript solves and the problems it does not.

Compare the two languages honestly: same runtime, different checking and tooling.

Place TypeScript in the 2012–2026 ecosystem and use current stable language features.

Install a modern TypeScript toolchain and create a checkable project.

Follow source through parse, check, and emit so you can debug diagnostics with confidence.

Write, check, and run a small TypeScript program end to end before adding more types.

Organize source, tests, and generated output so the compiler and humans agree.

Treat tsconfig as the project contract that defines which files are checked and how.

Use string, number, boolean, bigint, symbol, and object types with intent.

Let the checker infer local details and annotate the boundaries that other people call.

Choose let, const, and readonly so mutation is visible and intended.

Distinguish homogeneous lists from fixed-position tuples so index meaning stays explicit.

Prefer union literals for most catalogs and use enums only when a runtime object is required.

Use the four special types for escape hatches, boundaries, impossibility, and no useful value.

Make absence explicit with strictNullChecks instead of hoping values exist.

Compose values that can be one of several shapes, all of several shapes, or exact literals.

Write callable contracts with parameter and return types that callers can trust.

Make call sites honest about missing, defaulted, and variadic arguments.

Use overloads for a few distinct call shapes and avoid them when a union return is clearer.

Type functions that receive or return other functions without losing parameter information.

Describe object shapes as sets of properties rather than classes by default.

Name object contracts with type or interface according to composition needs.

Mark fields that may be missing and fields that must not be reassigned.

Type dictionaries carefully so known keys and open keys do not fight.

Build larger contracts from smaller ones without creating impossible intersections.

Choose the declaration form that matches merging, unions, and public API needs.

Predict assignability from shape, not from class or interface names.

Preserve relationships between reusable inputs and outputs with type parameters.

Design reusable operations and contracts whose type relationships remain visible.

Build stateful reusable abstractions while constraining required capabilities.

Derive keys and property types from existing contracts without duplication.

Select types from assignability relationships and model dependent contracts.

Transform object contracts systematically across their key sets.

Construct and parse constrained string contracts from known vocabularies.

Model nested structures whose children repeat the same shape.

Represent state machines with explicit variants and exhaustive handling.

Use runtime evidence to refine broad static types along control-flow paths.

Package trustworthy runtime checks into reusable narrowing functions.

Distinguish unchecked overrides from contract checking that preserves inference.

Create runtime objects with typed construction invariants and behavior.

Control class APIs and mutation while understanding compile-time and runtime privacy.

Separate class-wide behavior from incomplete base contracts that subclasses must finish.

Substitute specialized objects safely through stable behavioral contracts.

Protect invariants behind small behavioral APIs instead of exposing representation.

Assemble behavior from explicit collaborators instead of deep class hierarchies.

Organize code with standard static module boundaries and explicit dependencies.

Design stable module APIs with named, default, and re-export forms.

Load module namespaces asynchronously when execution reaches a feature boundary.

Understand how TypeScript maps import specifiers to source files and declarations.

Describe JavaScript and host-provided APIs without emitting implementation code.

Mark dependencies used only by the checker and clarify emitted module behavior.

Move a JavaScript codebase in slices without rewriting product behavior first.

Type-check JavaScript in place with JSDoc before a full rename to TypeScript.

Keep TypeScript and JavaScript modules working together during the transition.

Model HTTP contracts as compile-time types and validate payloads at the boundary.

Separate wire DTOs from domain models and reuse generic envelopes.

Make failure and paging states explicit so UI and clients cannot ignore them.

Build clients whose methods expose typed inputs after runtime validation of outputs.

Use schema libraries to prove unknown data before it enters typed code.

Type component inputs, state, and DOM events without fighting React's own types.

Preserve item types through reusable lists and custom hooks without collapsing to any.

Keep form state, validation, and API DTOs aligned without trusting the browser.

Use TypeScript as Angular's native language for components, services, and injection tokens.

Use HttpClient generics carefully and enable strict template checking.

Configure TypeScript for modern Node modules and a repeatable server typecheck.

Type ESM/CJS boundaries and treat process.env as unknown configuration.

Type handlers, params, and bodies without treating req.body as a trusted domain object.

Place TypeScript contracts in domain, application, and adapter layers.

Type asynchronous success and failure without losing the resolved value type.

Model parallel work, timeouts, and typed failure without any.

Turn on the options that make TypeScript a contract checker instead of a linter you can ignore.

Make absence and missing index results visible in the type system.

Explain target, module, moduleResolution, esModuleInterop, baseUrl, and paths.

Generate debug maps, public .d.ts files, and incremental caches with intent.

Split a large repo into referenced projects so checking stays incremental.

Write tests that fail compilation when public APIs drift and unsafe calls become legal.

Type mocks so they stay assignable to the ports they replace.

Mock HTTP at the boundary and keep domain tests free of fetch details.

Keep business types independent from transport types so JSON changes do not rewrite domain rules.

Share versioned contracts without creating a dump of every type.

Align TypeScript modules with domain language and inward dependencies.

Depend on typed ports so infrastructure can change without rewriting use cases.

Scale TypeScript across many packages with ownership and affected builds.

Govern types, builds, and boundaries for a multi-team TypeScript platform.

Speed up checking with incremental programs, not by turning off safety.

Separate erased types from JavaScript that actually ships and runs.

Keep a large TypeScript repo navigable for humans and the compiler.

Separate reviewability benefits from security controls so types are not treated as a firewall.

Draw the lines where data becomes trusted and validate there once.

Treat any, assertions, and untyped dependencies as risk, not convenience.

Model identity and permissions as data, then enforce them in executable code.

Apply the course to a catalog, cart, and checkout with validated payments.

Type learners, lessons, progress, and entitlements for TechLearningPro itself.

Ship a typed client with generated or handwritten contracts and runtime parsers.

Reuse one command type across a React UI, an Angular UI, and a Node API.

Integrate configuration, testing, boundaries, performance, and security into one design.

A sequenced practice set that compounds types, narrowing, APIs, and configuration.

Rehearse beginner through architect answers that explain reasoning and trade-offs.

Defend a TypeScript platform design with boundaries, packages, and fitness functions.

Check compile-time versus runtime thinking, unknown boundaries, configuration, and architecture judgments with instant feedback.