array_of_objects_filtering.js

let foo, bar, firstMethod, secondMethod; 

foo = [];
foo.push({ value: 'ua', long: 'Ukraine' });
foo.push({ value: 'en', long: 'USA' });
foo.push({ value: 'uk', long: 'United Kingom' });
foo.push({ value: 'ca', long: 'Canada' });
foo.push({ value: 'de', long: 'Germany' });

bar = [];
bar.push({ value: 'ca', long: 'Canada' });
bar.push({ value: 'en', long: 'USA' });


firstMethod = [];
foo.forEach(fooItem => {
  bar.some(barItem => { return fooItem.value === barItem.value; }) 
  || firstMethod.push(fooItem);
});

secondMethod = foo.filter(fooItem => {
  // return bar.map(barItem => barItem.value).indexOf(fooItem.value) === -1; //if [].includes is not defined
  return bar.map(barItem => barItem.value).includes(fooItem.value);
});

console.log('First Method: ', firstMethod);
console.log('Second Method: ', secondMethod);