useful-typescript-types

Types I'm tired of rewriting.

Table of Contents

- Utility Types
- ObjectPath
- Example
- ObjectPathContainsKey
- Example
- ValueAtObjectPath
- Example
- DeepPartial
- ArrayItem
- Tuple
- Example
- VariadicTuple
- Example
- Nullable
- RequiredProperties
- OmitFunctionKeys
- PickKeysByValue
- PickFunctionKeys
- PickObjectKeys
- PickArrayKeys
- PickStringKeys
- PickNumberKeys
- Mutable
- Immutable
- Syntactic Sugar Types
- Primitives
- Json
- JsonObject
- JsonArray
- Json Value
- Comparables
- Callback
- Example
- CallbackWithArgs
- Example
- Result
- Example
- Example
- Action
- Example

Utility Types

$3

Get the path keys of an object as string literals.

#### Example

``typescript
const myObj = {
foo: {
bar: "hi",
baz: "hello",
},
};

type MyObjPath = ObjectPath; // "foo" | "foo.bar" | "foo.baz"
`

$3

Get the path keys of an object that contains a certain key.

#### Example

`typescript
const myObj = {
foo: {
bar: {
baz: "hi",
},
},
};

type findBazPath = ObjectPathContainsKey; // "foo.bar"
`

$3

Get the value of an object at a certain path (using dot notation)

#### Example

`typescript
const myObj = {
foo: {
bar: {
baz: "hi",
},
},
} as const;

type baz = ValueAtPath; // "hi"
`

$3

Make all properties and nested properties of an object optional.

$3

Get the type of an array item.

$3

Define a tuple with exactly 2 elements of types T and N.

#### Example

`typescript
const tuple: Tuple = ["foo", 1];
`

$3

Define a tuple with a variable number of elements.

#### Example

`typescript
const vTuple: VariadicTuple = ["foo", 1, true];
`

$3

Define a type that can be null or of type T.

$3

Make all properties of an object required, removing optional modifiers.

$3

Omit keys of an object that have function values.

$3

Pick keys of an object that have Type values

`typescript
const obj = { foo: "bar", baz: 42 };

type MyKeys = PickKeysByValue; // "foo"
`

#### PickFunctionKeys

Pick keys of an object that have function values.

#### PickObjectKeys

Pick keys of an object that have object values.

#### PickArrayKeys

Pick keys of an object that have array values.

#### PickStringKeys

Pick keys of an object that have string values.

#### PickNumberKeys

Pick keys of an object that have number values.

$3

Remove readonly modifier from all properties of an object

$3

Make all properties of an object readonly

Syntactic Sugar Types

$3

Primitive types. Builds on top of Comparables.

$3

Json types.

#### JsonObject

A Json object consists of a JsonObject or JsonArray, which in turn consist of JsonValues.

#### JsonArray

A Json array consists of JsonValues.

#### Json Value

A Json value can be a string, number, boolean, null, JsonObject, or JsonArray.

$3

Primitive types that can be compared, including number, string, and BigInteger.

$3

A function that returns type T or void.

#### Example

`typescript
const myCallback: Callback = () => "foo";
`

$3

A function that returns type T or void and takes arguments of type Args.

#### Example

`typescript
const myCallback: CallbackWithArgs = (num, str) =>
"foo";
`

$3

A result type that can be either a success or an error.

#### Example

`typescript
const myResult: Result = { success: true, value: "foo" };
const myResult: Result = { success: false, error: 101 };
`

#### Example

`typescript
const myDict: Dictionary = { foo: "bar" };
`

$3

For state management systems like Redux, representing an action with a type and payload.

#### Example

`typescript
type Actions = Action<"INCREMENT", number> | Action<"DECREMENT", number>;
``