lodash toggle array element

toggle.js

/**
 * descructive
 * https://github.com/lodash/lodash/issues/1677
 */
function toggle(collection, item) {
  var idx = _.indexOf(collection, item);
  if(idx !== -1) {
    collection.splice(idx, 1);
  } else {
    collection.push(item);
  }
}

toggleItemInArray.js

// es6 version

import { indexOf, without } from 'lodash';

export default function toggleItemInArray(collection, item) {
  const index = indexOf(collection, item);
  if (index !== -1) {
    return without(collection, item);
  }
  return [...collection, item];
}




// tests
import toggleItemInArray from '../toggleItemInArray';

it('toggles item properly', () => {
  expect(toggleItemInArray([], 'a')).toEqual(['a']);
  expect(toggleItemInArray(['a', 'b'], 'a')).toEqual(['b']);
});

usingXor.js

// lodash xor

_.xor([1], [2]); // = [1, 2]

_.xor([1, 2], [2]); // = [1]

_.xor([1], [2]);
= [1, 2]

_.xor([1, 2], [2]);
= [1]

Oh yeah, _.xor seems like a much better option 😃