JS Calculate memory size for object

calcSizeInMemory.js

function calcSizeInMemory(obj) {
  const visited = new Set();

  function sizeOf(obj) {
    if (obj === null || obj === undefined) return 0;

    switch (typeof obj) {
      case "number":
        return 8;
      case "string":
        return obj.length * 2;
      case "boolean":
        return 4;
      case "object":
        if (visited.has(obj)) return 0;
        visited.add(obj);

        let bytes = 0;
        const objClass = Object.prototype.toString.call(obj).slice(8, -1);

        if (objClass === "Object" || objClass === "Array") {
          for (const key in obj) {
            if (!Object.hasOwnProperty.call(obj, key)) continue;
            bytes += sizeOf(key); // count key size
            bytes += sizeOf(obj[key]);
          }
        } else if (objClass === "Date") {
          bytes += 8;
        } else if (objClass === "Set" || objClass === "Map") {
          for (const item of obj) {
            bytes += sizeOf(item);
          }
        } else if (typeof Buffer !== "undefined" && Buffer.isBuffer(obj)) {
          bytes += obj.length;
        } else {
          bytes += obj.toString().length * 2;
        }
        return bytes;
      default:
        return 0;
    }
  }

  function formatByteSize(bytes) {
    if (bytes < 1024) return bytes + " bytes";
    else if (bytes < 1048576) return (bytes / 1024).toFixed(3) + " KiB";
    else if (bytes < 1073741824) return (bytes / 1048576).toFixed(3) + " MiB";
    else return (bytes / 1073741824).toFixed(3) + " GiB";
  }

  return formatByteSize(sizeOf(obj));
}