Typeseedcordv0.10.6

PickIndexSignature

Pick only index signatures from the given object type, leaving out all explicitly defined properties.

This is the counterpart of OmitIndexSignatureOmitIndexSignature.

type PickIndexSignature<ObjectType> = {
    [KeyType in keyof ObjectType as {} extends Record<
        KeyType,
        unknown
    >
        ? KeyType
        : never]: ObjectType[KeyType];
};

type PickIndexSignature<ObjectType> = {
    [KeyType in keyof ObjectType as {} extends Record<
        KeyType,
        unknown
    >
        ? KeyType
        : never]: ObjectType[KeyType];
};

import type {PickIndexSignature} from 'type-fest';

declare const symbolKey: unique symbol;

type Example = {
	// These index signatures will remain.
	[x: string]: unknown;
	[x: number]: unknown;
	[x: symbol]: unknown;
	[x: `head-${string}`]: string;
	[x: `${string}-tail`]: string;
	[x: `head-${string}-tail`]: string;
	[x: `${bigint}`]: string;
	[x: `embedded-${number}`]: string;

	// These explicitly defined keys will be removed.
	['kebab-case-key']: string;
	[symbolKey]: string;
	foo: 'bar';
	qux?: 'baz';
};

type ExampleIndexSignature = PickIndexSignature<Example>;
// {
// 	[x: string]: unknown;
// 	[x: number]: unknown;
// 	[x: symbol]: unknown;
// 	[x: `head-${string}`]: string;
// 	[x: `${string}-tail`]: string;
// 	[x: `head-${string}-tail`]: string;
// 	[x: `${bigint}`]: string;
// 	[x: `embedded-${number}`]: string;
// }

import type {PickIndexSignature} from 'type-fest';

declare const symbolKey: unique symbol;

type Example = {
	// These index signatures will remain.
	[x: string]: unknown;
	[x: number]: unknown;
	[x: symbol]: unknown;
	[x: `head-${string}`]: string;
	[x: `${string}-tail`]: string;
	[x: `head-${string}-tail`]: string;
	[x: `${bigint}`]: string;
	[x: `embedded-${number}`]: string;

	// These explicitly defined keys will be removed.
	['kebab-case-key']: string;
	[symbolKey]: string;
	foo: 'bar';
	qux?: 'baz';
};

type ExampleIndexSignature = PickIndexSignature<Example>;
// {
// 	[x: string]: unknown;
// 	[x: number]: unknown;
// 	[x: symbol]: unknown;
// 	[x: `head-${string}`]: string;
// 	[x: `${string}-tail`]: string;
// 	[x: `head-${string}-tail`]: string;
// 	[x: `${bigint}`]: string;
// 	[x: `embedded-${number}`]: string;
// }

ObjectType

ObjectType

ObjectType

import type {PickIndexSignature} from 'type-fest'; declare const symbolKey: unique symbol; type Example = { // These index signatures will remain. [x: string]: unknown; [x: number]: unknown; [x: symbol]: unknown; [x: `head-${string}`]: string; [x: `${string}-tail`]: string; [x: `head-${string}-tail`]: string; [x: `${bigint}`]: string; [x: `embedded-${number}`]: string; // These explicitly defined keys will be removed. ['kebab-case-key']: string; [symbolKey]: string; foo: 'bar'; qux?: 'baz'; }; type ExampleIndexSignature = PickIndexSignature<Example>; // { // [x: string]: unknown; // [x: number]: unknown; // [x: symbol]: unknown; // [x: `head-${string}`]: string; // [x: `${string}-tail`]: string; // [x: `head-${string}-tail`]: string; // [x: `${bigint}`]: string; // [x: `embedded-${number}`]: string; // }