The first sequence of the join operation.
The second sequence of the join operation.
Function that projects the key given an element of one of the sequences to join.
Function that projects the result given just an element from first where there is no corresponding element in second.
Function that projects the result given an element from first and an element from second that match on a common key.
OptionalequalityComparer: EqualityComparer<TKey>A function to compare keys.
A sequence containing results projected from a left outer join of the two input sequences.
type Person = { name: string };
type Pet = { name: string; owner: Person };
const magnus: Person = { name: 'Magnus' };
const terry: Person = { name: 'Terry' };
const adam: Person = { name: 'Adam' };
const john: Person = { name: 'John' };
const barley: Pet = { name: 'Barley', owner: terry };
const boots: Pet = { name: 'Boots', owner: terry };
const whiskers: Pet = { name: 'Whiskers', owner: adam };
const daisy: Pet = { name: 'Daisy', owner: magnus };
const scratchy: Pet = { name: 'Scratchy', owner: { name: 'Bob' } };
const people = from([magnus, terry, adam, john]);
const pets = from([barley, boots, whiskers, daisy, scratchy]);
const result = leftJoinHomogeneous<Pet, Person, { ownerName: string; pet: string | null }>(
people,
pets,
person => person,
pet => pet.owner,
person => ({ ownerName: person.name, pet: null }),
(person, pet) => ({ ownerName: person.name, pet: pet.name })
)
.toArray();
expect(result).toEqual([
{ ownerName: 'Magnus', pet: 'Daisy' },
{ ownerName: 'Terry', pet: 'Barley' },
{ ownerName: 'Terry', pet: 'Boots' },
{ ownerName: 'Adam', pet: 'Whiskers' },
{ ownerName: 'John', pet: null }
]);
Performs a left outer join on two homogeneous sequences.