Undefined-to-null NPM

undefined-to-null

Convert undefined properties of an object to null and back again.

Why would I want this?

There are a fair number of arguments for using undefined over null. However, some libraries, endpoints, and other tools require null, either because of the preference of that developer or a detail of how the properties are handled. Basically, I got tired of having to write

someFunctionThatNeedsNull({
  // Some value that might be undefined needs to be coerced to null.
  a: potentiallyUndefinedValue ?? null,
  // Potentially undefined value that could otherwise use shorthand notation can't, because it has to be coerced to null.
  b: b ?? null,
  // Optional chaining needs to be coerced to null.
  c: potentiallyNullOrUndefinedValue?.someProperty ?? null,
  // The results of inlined functions that return undefined need to bo coerced to null.
  d:
    someArrayOfElements.find((element) => elementIsTheOneIWant(element)) ??
    null,
});

and am willing to write

someFunctionThatNeedsNull(
  undefinedToNull({
    a: potentiallyUndefinedValue,
    b,
    c: potentiallyNullOrUndefinedValue?.someProperty,
    // Bonus: Prettier doesn't force this to multiple lines now.
    d: someArrayOfElements.find((element) => elementIsTheOneIWant(element)),
  }),
);

Install

npm install undefined-to-null

Or, with yarn:

$ yarn add undefined-to-null

Or pnpm:

$ pnpm install undefined-to-null

Usage

import {nullToUndefined, undefinedToNull} from 'undefined-to-null';

const output = undefinedToNull({foo: undefined});
assert(output.foo === null);

// And back again.
const backAgain = nullToUndefined(output);
assert(backAgain.foo === undefined);
// It's no trick, the property's still there.
assert('foo' in backAgain);