option-t/esm/undefinable/operators/xor.js

A toolkit of Nullable/Option/Result type implementation in ECMAScript. Their APIs are inspired by Rust's `Option<T>` and `Result<T, E>`.

import { isNotUndefined } from '../core/undefinable.js';
/**
 *  Return one of this pattern:
 *
 *  1. a=others, b=undefined => _a_
 *  2. a=undefined, b=others => _b_
 *  3. Others => `undefined`
 */
export function xorForUndefinable(a, b) {
    const aIsSome = isNotUndefined(a);
    const bIsSome = isNotUndefined(b);
    if (aIsSome && !bIsSome) {
        return a;
    }
    if (!aIsSome && bIsSome) {
        return b;
    }
    return undefined;
}