2705. Compact Object

Given a JSON-compatible object or array obj, return a compact version of the object — one without any falsy values at any level.

📄 Problem Statement

A compact object is one that has all falsy values removed recursively:

Falsy values include: false, 0, "", null, undefined, and NaN.
Nested objects and arrays must also be compacted.
The input is guaranteed to be valid JSON (i.e., no functions or undefined outside of parsing context).
Arrays are treated as objects with numeric keys and must also be filtered.

💡 Example


const obj = {
  a: null,
  b: [false, 1],
  c: {
    d: 0,
    e: "test",
    f: {
      g: NaN,
    }
  }
};

compactObject(obj);
// ➞ {
//   b: [1],
//   c: {
//     e: "test"
//   }
// }

🧠 Explanation

Recursively iterate through all keys of the object:

If the value is an object or array, apply compactObject() recursively.
If the result is still truthy, include it in the result.
For arrays, only keep values that are truthy or resolve to truthy after recursion.

The logic leverages Boolean(value) to check for truthiness.

✅ Your Solution


/**
 * @param {Object|Array} obj
 * @return {Object|Array}
 */
var compactObject = function(obj) {
    if (Array.isArray(obj)) {
        return obj
            .map(item => compactObject(item))
            .filter(Boolean);
    } else if (obj !== null && typeof obj === "object") {
        const res = {};
        for (const [key, value] of Object.entries(obj)) {
            const compacted = compactObject(value);
            if (Boolean(compacted)) {
                res[key] = compacted;
            }
        }
        return res;
    }
    return obj;
};