info/learnxinyminutes-docs
1
0
Fork 0
mirror of https://github.com/adambard/learnxinyminutes-docs.git synced 2025-08-09 08:16:58 +02:00
Code Issues Releases Wiki Activity

[typescript/en] Add tagged union types

Browse Source 
They're super useful.

https://www.typescriptlang.org/docs/handbook/advanced-types.html#discriminated-unions
https://mariusschulz.com/blog/typescript-2-0-tagged-union-types
This commit is contained in:
Piotr Monwid-Olechnowicz
2019-07-03 23:15:10 +02:00
committed by GitHub
parent 84cb0e8899
commit 96b65fb40d
1 changed files with 13 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
typescript.html.markdown
View File

@@ -224,6 +224,19 @@ moreNumbers.push(5); // Error, no push method (because it mutates array)
moreNumbers.length = 3; // Error, length is read-only moreNumbers.length = 3; // Error, length is read-only
numbers = moreNumbers; // Error, mutating methods are missing numbers = moreNumbers; // Error, mutating methods are missing
// Tagged Union Types for modelling state that can be in one of many shapes
type State =
| { type: "loading" }
| { type: "success", value: number }
| { type: "error", message: string };
declare const state: State;
if (state.type === "success") {
console.log(state.value);
} else if (state.type === "error") {
console.error(state.message);
}
// Iterators and Generators // Iterators and Generators
// for..of statement // for..of statement