Type Alias Merge<Destination, Source>

Merge: Destination extends unknown
    ? Source extends unknown
        ? If<
            IsEqual<Destination, Source>,
            Destination,
            _Merge<Destination, Source>,
        >
        : never
    : never

Merge two types into a new type. Keys of the second type overrides keys of the first type.

Type Parameters

Destination
Source

Example

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

type Foo = {
	[x: string]: unknown;
	[x: number]: unknown;
	foo: string;
	bar: symbol;
};

type Bar = {
	[x: number]: number;
	[x: symbol]: unknown;
	bar: Date;
	baz: boolean;
};

export type FooBar = Merge<Foo, Bar>;
//=> {
// 	[x: string]: unknown;
// 	[x: number]: number;
// 	[x: symbol]: unknown;
// 	foo: string;
// 	bar: Date;
// 	baz: boolean;
// }

Note: If you want a merge type that more accurately reflects the runtime behavior of object spread or Object.assign, refer to the ObjectMerge type.

See

ObjectMerge