Approximate size of object in JS using TypeScript (in KB)

size_of.es6

const typeSizes = {
    "undefined": () => 0,
    "boolean": () => 4,
    "number": () => 8,
    "string": item => 2 * item.length,
    "object": item => !item ? 0 : Object
      .keys(item)
      .reduce((total, key) => sizeOf(key) + sizeOf(item[key]) + total, 0)
};

export const sizeOf = value => typeSizes[typeof value](value);