22 Filter an object and return key-value pairs that pass the filter

filter_object.js

function filterObject(obj, fn){
  return Object.keys(obj).filter((key) => {
    var e = obj[key];
    return fn(e);
  }).map((e) => {
    return {
      key: e,
      value: obj[e]
    };
  });
}

var obj = {
  a:1,
  b:2,
  c:{
    d:4
  }
}

// test
var result = filterObject(obj, (e) => {
  return e.d == 4;
});
console.log(result);

// result:  [ { key: 'c', value: { d: 4 } } ]