redux-utils.js

export const contains = (list = [], test) => list.indexOf(test) >= 0;

export const removeItemAt = (list = [], index = 0) =>
  [
    ...list.slice(0, index),
    ...list.slice(index + 1),
  ];

export const insertItemAt = (list = [], index = 0, item) =>
  [
    ...list.slice(0, index),
    item,
    ...list.slice(index),
  ];

export const replaceItemAt = (list = [], index = 0, item) =>
  [
    ...list.slice(0, index),
    item,
    ...list.slice(index + 1),
  ];