leftJoin

leftJoin(left, right, leftKeyFn, rightKeyFn) → array · Array

Left join – returns all items from the left array, with matching items from the right (or null for non-matches).

• left (required): left array (all items preserved)

• right (required): right array

• leftKeyFn (required): lambda extracting key from left items

• rightKeyFn (required): lambda extracting key from right items

let customers = [{id: 1, name: "Alice"}, {id: 2, name: "Bob"}]
let orders = [{customerId: 1, product: "Widget"}]

{
  result: leftJoin(customers, orders, (c) -> c.id, (o) -> o.customerId)
  // [{l: {id: 1, name: "Alice"}, r: {customerId: 1, product: "Widget"}},
  //  {l: {id: 2, name: "Bob"}, r: null}]
}