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(De)serializing sets, maps and dates using replacer/reviver (TypeScript)
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const enum Mark { | |
Set = '@set', | |
Map = '@map', | |
Date = '@date' | |
} | |
type Serialized<M extends Mark, S = unknown> = [mark: M, value: S] | |
type Codec<T, S> = { | |
serialize(value: T): Serialized<Mark, S> | |
deserialize(value: S): T | |
} | |
const SetCodec: Codec<Set<unknown>, unknown[]> = { | |
serialize: (value) => [Mark.Set, [...value]], | |
deserialize: (values) => new Set(values) | |
} | |
const MapCodec: Codec<Map<string, unknown>, [string, unknown][]> = { | |
serialize: (value) => [Mark.Map, [...value.entries()]], | |
deserialize: (values) => new Map(values) | |
} | |
const DateCodec: Codec<Date, string> = { | |
serialize: (value) => [Mark.Date, value.toISOString()], | |
deserialize: (value) => new Date(value) | |
} | |
const isSet = (value: unknown): value is Serialized<Mark.Set, unknown[]> => | |
Array.isArray(value) && value[0] === Mark.Set | |
const isMap = (value: unknown): value is Serialized<Mark.Map, [string, unknown][]> => | |
Array.isArray(value) && value[0] === Mark.Map | |
const isDate = (value: unknown): value is Serialized<Mark.Date, string> => | |
Array.isArray(value) && value[0] === Mark.Date | |
function serialize(value: unknown): string { | |
return JSON.stringify(value, function (this: any, key: string, value: unknown) { | |
if (value instanceof Set) return SetCodec.serialize(value) | |
if (value instanceof Map) return MapCodec.serialize(value) | |
if (this[key] instanceof Date) return DateCodec.serialize(this[key]) | |
return value | |
}) | |
} | |
function deserialize<T = unknown>(value: string): T { | |
return JSON.parse(value, function (this: any, key: string, value: unknown) { | |
const raw = this[key] as unknown | |
if (isSet(raw)) return SetCodec.deserialize(raw[1]) | |
if (isMap(raw)) return MapCodec.deserialize(raw[1]) | |
if (isDate(raw)) return DateCodec.deserialize(raw[1]) | |
return value | |
}) as T | |
} |
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