Discover advanced TypeScript concepts: Gain insights into compiler flags, generic types, and discriminated unions. Delve into writing error-free code and mastering complex error messages with confidence.

typescript-3.7.5.tar.gz

TypeScript 3.7.5 Strict

TypeScript 3.7.5

Are you using TypeScript, but feel like you’re not making the most out of it? Do you find some advanced TypeScript concepts confusing? Do you get lost looking at complex type errors?

If you answered “yes” to any of these questions, then this course is for you! It introduces you to the world of advanced TypeScript concepts including: compiler flags for catching more errors, generic types, and how to compose types with discriminated unions. 

After finishing this course, you’ll feel more confident in your TypeScript skills. You will be able to write types that detect whole classes of possible runtime errors at compile time. Typing even the most untypeable JavaScript code will be a no brainer for you, and you’ll be fluent in TypeScript error messages.

Advanced TypeScript Masterclass

# Overview

Type guard is not really a _type_ so much as it is a mechanism that _narrows types_.

TypeScript soars at analyzing your code and deducing information based on it. Oftentimes, TypeScript can analyze a conditional expression (or an `if` statement) and narrow the type of the tested value inside the branches of the condition. We've already seen this happen with discriminated unions. This mechanism is referred to as _type guard_. 

# Nullable type guard

We've already seen the nullable type guard in action when discussing `strictNullChecks`. Nullable type guard removes optionality from the type of some value if this value is previously tested for nullability. In the below example, if the `name` is truthy (i.e., not `null` or `undefined`), its type is narrowed to `string` inside the positive branch of the `if` statement.

This lesson introduces the concept of type guards.

Strict types

Generics

Composing types

Advanced types

TypeScript in practice

Conclusion

Type Guards

Overview