@tpluscode/rdfine/lib/filter.js

RDF/JS idiomatic, native, effective

export function onlyUnique(areEqual) {
    return function (value, index, self) {
        if (Array.isArray(value)) {
            return true;
        }
        const found = self.findIndex(other => {
            if (Array.isArray(other)) {
                return true;
            }
            return areEqual(value, other);
        });
        return found === index;
    };
}