<?php
$array1 = array("a" => "green", "red", "blue");
$array2 = array("b" => "green", "yellow", "red");
$result = array_intersect($array1, $array2);
print_r($result);

let a = ['my', 'life', 'sucks', 'so', 'hard'];
let b = ['life', 'sucks', 'hard'];

const intersect = (leftArray, rightArray) => leftArray.filter(value => rightArray.indexOf(value) > -1);