JSFiddle - React, Tailwind, and code Playground

JavaScript

var posts = [
 {area: 'NY', name: 'Bla', ads: true},
 {area: 'DF', name: 'SFS', ads: false},
 {area: 'TT', name: 'SDSD', ads: true},
 {area: 'SD', name: 'Engine', ads: false},
 {area: 'NSK', name: 'Toyota', ads: false},
];
var filter = ['NY', 'SD'];

function filtered() {
  return posts
     .filter(function(post){
        return post.ads === true;
     })
     .filter(function(post){
        return filter.indexOf(post.area) > 0;
     })
}

console.log(filtered());