coalesceFactory javascript Code Snippet in 2025

Customizes a coalesce function that returns the first argument which is true based on the given validator.

• Use Array.prototype.find() to return the first argument that returns true from the provided argument validation function, valid.

const coalesceFactory = valid => (...args) => args.find(valid);

const customCoalesce = coalesceFactory(
  v => ![null, undefined, '', NaN].includes(v)
);
customCoalesce(undefined, null, NaN, '', 'Waldo'); // 'Waldo'