@prismicio/babel-transform-config/plugin/utils.js

Transform JS config files (Next, Nuxt, Gatsby)

const ArrayHelpers = {
  splitAtLast(array) {
    if (!array) return null;

    switch (array.length) {
      case 0:
        return [[], null];
      case 1:
        return [[], array[0]];
      default:
        return [array.slice(0, -1), array[array.length - 1]];
    }
  },

  splitAtHead(array) {
    if (!array) return null;

    switch (array.length) {
      case 0:
        return [null, []];
      case 1:
        return [array[0], []];
      default:
        return [array[0], array.slice(1)];
    }
  },

  combine(array1, array2, mergeFn) {
    // FIXME: Behaving really weirdly / not used
    const [main, other] =
      array1.length > array2.length ? [array2, array1] : [array1, array2];

    return main
      .map((value, index) => mergeFn(value, other[index]))
      .concat(
        other
          .slice(main.length, other.length)
          .map(value => mergeFn(undefined, value))
      );
  },

  flatten(arr) {
    return arr.reduce((acc, subArr) => acc.concat(subArr), []);
  },

  distinct(arr1, arr2, predicate) {
    return arr1.concat(arr2).reduce((acc, current) => {
      for (const item of acc) {
        if (predicate(item, current)) {
          return acc;
        }
      }
      acc.push(current);
      return acc;
    }, []);
  },

  diff(array1, array2) {
    return array1.filter(function (elm) {
      return array2.indexOf(elm) === -1;
    });
  }
};

module.exports = {
  ArrayHelpers
};