unnullish

unnullish provided by this package returns the value as is if value is nullish, otherwise it executes callback and returns the result. It is an opposite function of the nullish coalescing operator (??).

Usage

unnullish

unnullish<T, R>(value: T | null | undefined, callback(v: T) => R): R | null | undefined

The function is useful when you want to apply some transformation functions to optional values. For example,

import { unnullish } from "https://deno.land/x/unnullish/mod.ts";

type Options = {
  foo?: string;
  bar?: boolean;
};

const options: Options = {
  foo: unnullish(Deno.env.get("foo"), (v) => v.toUpperCase()),
  // instead of
  //foo: Deno.env.get("foo") != null
  //  ? Deno.env.get("foo").toUpperCase()
  //  : undefined,

  bar: unnullish(Deno.env.get("bar"), (v) => parseInt(v, 10)),
  // instead of
  //bar: Deno.env.get("bar") != null
  //  ? parseInt(Deno.env.get("bar"), 10)
  //  : undefined,
};

Note that the function returns null or undefined as is, mean that you may need to use nullish coalescing operator to normalize the result. For example,

import { unnullish } from "https://deno.land/x/unnullish/mod.ts";

console.log(unnullish(null, () => 0));
// -> null
console.log(unnullish(undefined, () => 0));
// -> undefined

console.log(unnullish(null, () => 0) ?? undefined);
// -> undefined
console.log(unnullish(undefined, () => 0) ?? undefined);
// -> undefined

License

The code follows MIT license written in LICENSE. Contributors need to agree that any modifications sent in this repository follow the license.