// provides some utility array functions ... if this gets too big we can just start

// using lodash or something, but so far we don't really need all that much

'use strict';

module.exports = {

// does array1 and array2 have at least element in common?

hasCommonElement: function(array1, array2) {

return array1.find(elem => {

return array2.includes(elem);

});

},

// does array1 have all the elements in array2 (is it a superset)?

hasAllElements: function(array1, array2) {

return !array2.find(elem => {

return !array1.includes(elem);

});

},

// get all the elements in array1 that are not in array2

difference: function(array1, array2) {

return array1.filter(elem => !array2.includes(elem));

},

// get all the elements in array1 that are also in array2

intersection: function(array1, array2) {

return array1.filter(elem => array2.includes(elem));

},

// get all the elements in array1 and all the elements in array2,

// but avoid redundancies

union: function(array1, array2) {

return array1.concat(array2.filter(elem => !array1.includes(elem)));

},

unique: function(arr) {

return arr.reduce((a, elem) => {

if (a.indexOf(elem) === -1) {

a.push(elem);

}

return a;

}, []);

}

};