Typesafe path to variable
Implementation of microsoft/TypeScript#20423
There is limitations for 2 level deep with type hacks, so no infinit tuples
npm i ts-pathof --save-exact
import { pathOf } from 'ts-pathof';
const c = { z: { y: { bb: 123 }}};
const path = pathOf(c, 'z', 'y', 'bb');
// path now is typeof [ 'z', 'y', 'bb' ]
const path2 = pathOf(c, 'z', 'y', 'gg'); // error, because no 'gg' field in c.z.yMaximum 10 levels deep limitation on pathOf
import { hasPath } from 'ts-pathof';
const c = { z: { y: { bb: 123 }}};
const path = hasPath(c, [ 'z', 'y', 'bb' ]); // ok
const path2 = hasPath(c, [ 'z', 'y', 'gg' ]); // false & compilation errorMaximum 20 levels deep limitation on hasPath
Use pathOfN (where N is deep), to pick tuple-type path to field
Maximum 10 levels deep
Eg:
let path: pathOf3<typeof c, 'z', 'y', 'bb'>;
path = pathOf(c, 'z', 'y', 'bb');Use other type-only variant (with 20 levels limitation on deep), PathOf:
const o = {x: { y: 10 }};
type xy = PathOf<typeof o, ['x', 'y']>; // ok
type xyz = PathOf<typeof o, ['x', 'y', 'z']>; // errorCheck out typedpark, and Variadic Kinds thread for more info on advenced tuple utils.
Eg picking head or tail of tuple, reverse or join.
type composed = Compose<[boolean, string], [number]>;
composed -> [boolean, string, number]Also checkout tsargs, utility types for arguments.
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