Serialise/Deserialise JavaScript Maps and Sets

mapSetSerialiseDeserialise.js

function replacer(key, value) {
  if (value instanceof Map) {
    return { __type: 'Map', value: Object.fromEntries(value) }
  }
  if (value instanceof Set) {
    return { __type: 'Set', value: Array.from(value) }
  }
  return value
}

function reviver(key, value) {
  const resultMap = {
   'Set': new Set(value.value),
   'Map': new Map(Object.entries(value.value)),
   'default': value
  };
  
  return resultMap[value?.__type] || resultMap.default;
}


// Serialise
JSON.stringify(obj, replacer)

// Deserialise
JSON.parse(string, reviver)