Calculate Memory Size of a JS Object

memorySizeOf.ts

function memorySizeOf(obj: any) {
  const seen = new WeakSet<object>();

  function sizeOf(value: any): number {
    if (value === null || value === undefined) return 0;

    const t = typeof value;
    if (t === "number" ) return 8;
    if (t === "boolean") return 4;
    if (t === "bigint" ) return 8;
    if (t === "string" ) return new TextEncoder().encode(value).length;
    if (t === "function" || t === "symbol") return 0;

    if (value instanceof ArrayBuffer) return value.byteLength;
    if (ArrayBuffer.isView(value)) return (value as ArrayBufferView).byteLength || 0;

    if (t === "object") {
      if (seen.has(value)) return 0;
      seen.add(value);

      let total = 0;
      if (Array.isArray(value)) {
        for (const item of value) total += sizeOf(item);
        return total;
      }
      for (const [k, v] of Object.entries(value)) {
        total += sizeOf(k);
        total += sizeOf(v);
      }
      return total;
    }

    return 0;
  }

  return sizeOf(obj);
}