Calculate Memory Size of a JS Object

memorySizeOf.js

function memorySizeOf(obj) {
  var bytes = 0;

  function sizeOf(obj) {
    if (obj !== null && obj !== undefined) {
      switch (typeof obj) {
        case "number":
          bytes += 8;
          break;
        case "string":
          bytes += obj.length * 2;
          break;
        case "boolean":
          bytes += 4;
          break;
        case "object":
          var objClass = Object.prototype.toString.call(obj).slice(8, -1);
          if (objClass === "Object" || objClass === "Array") {
            for (var key in obj) {
              if (!obj.hasOwnProperty(key)) continue;
              sizeOf(obj[key]);
            }
          } else bytes += obj.toString().length * 2;
          break;
      }
    }
    return bytes;
  }

  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));
}