remove null properties from a nested json object

json-parse-remove-null.js

/*Remove null properties from a nested json object*/
function parse(input) {
  if (
    input == null ||
    (Array.isArray(input) && input.length == 0) ||
    JSON.stringify(input) == "{}"
  ) {
    return null;
  }
  if (typeof input === "object" && Array.isArray(input) == false) {
    let result = null;
    Object.keys(input).forEach((key) => {
      const value = parse(input[key]);
      if (value != null) {
        result = result || {};
        result[key] = value;
      }
    });
    return result;
  } else if (Array.isArray(input)) {
    if (input.length > 0) {
      const a = [];
      input.forEach((e) => {
        const v = parse(e);
        if (v != null) a.push(v);
      });
      return a;
    } else return null;
  } else return input;
}


const person = {
  name: "John",
  age: 30,
  married: true,
  retired: false,
  kids: ["Ann", "Billy"],
  dogs: null,
  cats: 0,
  properties: { homes: [], rentals: [] },
  cars: [
    { model: "BMW 230", mpg: 27.5, vin: "", manual: false },
    { model: "Ford Edge", mpg: 24.1, features: [] },
    [{ model: "Tesla Model S", mpg: null }],
    [null, ""],
    false,
    null,
  ],
};
const out = parse(person);
console.log(out); 
// {
//   name: "John",
//   age: 30,
//   married: true,
//   retired: false,
//   kids: ["Ann", "Billy"],
//   cats: 0,
//   cars: [
//     { model: "BMW 230", mpg: 27.5, vin: "", manual: false },
//     { model: "Ford Edge", mpg: 24.1 },
//     [{ model: "Tesla Model S" }],
//     [""],
//     false,
//   ],
// };