TypeScript Fundamentals — Getting a Bit Deeper
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In this episode of Syntax, Scott and Wes continue their discussion of TypeScript Fundamentals with a deeper diver into more advanced use cases.
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Show Notes Deep end stuff03:30 - any vs unknown
06:20 - never
- https://twitter.com/Igorbdsq/status/1351681019196436482 09:14 - .d.ts
- Definition files
- Usually for existing libraries that don’t have types
- Can be generated or hand-written
- Also really handy for pure JS projects, you still get good autocomplete because of these
13:25 - Type generation
- Can be generated from GraphQL, or Schemas, or from JSON Output
17:20 - TypeScript generics (variables)
- Kind of like functions, they return something different based on what you pass it
- makeFood
- makeFood
- This function makes food and shares lots of the same functionality between making a pizza and sandwich
- If the only thing that differs is the type returned, we can use generics
- You often see this as a single char T
- It can be anything
- Promise is a generic
- querySelector uses generics
21:48 - Promises / Async + Await
- Functions now return a Promise type, but with a generic
- Promise
- Promise
- Promise, Request, Request
- stringified
- added headers
29:48 - Type assertion (type casting)
- Type assertion is when you want to tell TypeScript “Hey I know better than you”.
- Two ways:
- as keyword (most popular)
- someValue as HTMLParagraphElement
- Tagged before
- someValue
- as keyword (most popular)
34:14 - TypeScript without TypeScript (JSDoc / TSDoc)
- Really nice!
- You can also add comments / descriptions
- https://github.com/developit/redaxios/blob/master/src/index.js
40:08 - Interfaces vs Types
- Interfaces have better perf
- https://twitter.com/wesbos/status/1362418379919937545
- https://blog.logrocket.com/types-vs-interfaces-in-typescript/
- What do you default to?
44:27 - Interface or Types
- Scott - Types
- Wes - Interfaces
44:50 - any vs unknown
- Scott - any
- Wes - unknown / any
46:52 - Any (No Implicit or Implicit Allowed)
- Scott - No implicit any
- Wes - No implicit any
48:31 - Return types (Implicit or Explicit)
- Scott - Explicit always
- Wes - Not always
50:49 - Compile (TSC, Strip TS)
- Scott - Strip
- Wes - Both
52:38 - Type Assertion (as or )
- Scott - as
- Wes - as
53:09 - Arrays (Dog[] or Array)
- Scott - Dog[]
- Wes - Dog[]
54:02 - Assert or Generic (if both work)
- querySelector(’.thing’) as HTMLVideoElement; or querySelector(’.thing’);
- Scott - querySelector(’.thing’);
- Wes - querySelector(’.thing’);
- Syntax 324: TypeScript Fundamentals
- Syntax 327: Hasty Treat - TypeScript Compilers and Build Tools
- Axios
- VS Code
- Syntax 310: Serverless, Deno and TypeScript with Brian Leroux
- Cloudinary
- Notion
- Scott: Powerowl 16 Battery Recharger
- Wes: Fairywill Pro P11
- Scott: Level 2 Node Authentication - Sign up for the year and save 25%!
- Wes: Beginner Javascript - Use the coupon code ‘Syntax’ for $10 off!
- Scott’s Instagram
- LevelUpTutorials Instagram
- Wes’ Instagram
- Wes’ Twitter
- Wes’ Facebook
- Scott’s Twitter
- Make sure to include @SyntaxFM in your tweets
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