Optionals

Optionals are a good way of ensuring that no excessive data is stored as binary.

They are encoded as:

• 0 given value === undefined.
• 1 encoded(value) given value !== undefined.

import bin from 'typed-binary';

const buffer = Buffer.alloc(16);
const writer = new bin.BufferWriter(buffer);
const reader = new bin.BufferReader(buffer);

// Simple object schema
const Address = bin.object({
  city: bin.string,
  street: bin.string,
  postalCode: bin.string,
});

// Simple object schema (with optional field)
const Person = bin.object({
  firstName: bin.string,
  lastName: bin.string,
  age: bin.i32,
  address: bin.optional(Address),
});

// Writing a Person (no address)
Person.write(writer, {
  firstName: 'John',
  lastName: 'Doe',
  age: 43,
});

// Writing a Person (with an address)
Person.write(writer, {
  firstName: 'Jesse',
  lastName: 'Doe',
  age: 38,
  address: {
    city: 'New York',
    street: 'Binary St.',
    postalCode: '11-111',
  },
});

console.log(JSON.stringify(Person.read(reader).address)); // undefined
console.log(JSON.stringify(Person.read(reader).address)); // { "city": "New York", ... }