TypeSeq

TypeSeq is a compact, deterministic serialization format for flat JavaScript objects.

It encodes values together with explicit type aliases, producing stable and human-readable strings that can be decoded back into predictable runtime values. TypeSeq is designed for cases where JSON is too verbose, unstable, or ambiguous.

Key characteristics

• Type-aware: each value carries its type (string, number, boolean, date, null)

• Deterministic output: keys are sorted, encoding is stable

• Null-safe: non-finite numbers decode as null

• Undefined skipped: undefined keys are omitted during encoding

• TypeScript-friendly: optional schema-based decoding with accurate inference

• Readable: plain-text format, easy to inspect and debug

When to use TypeSeq

• Stable cache keys

• URL-safe or compact payload transport

• Deterministic hashing or signatures

• Simple protocols where full JSON is unnecessary

When not to use it

• Nested or deeply structured data

• Binary-heavy payloads

• Cases that require full JSON compatibility

Quick example

Installation

npm

npm i typeseq

yarn

yarn add typeseq

Encode

import { encode, decode, decodeWithSchema } from 'typeseq'

const payload = {
	name: 'Yanto Kopling',
	age: 27,
	score: NaN, // non-finite → null
	active: true,
	createdAt: new Date('2025-12-29T10:00:00Z'),
	note: undefined, // skipped
	deletedAt: null // explicit null
}

const encoded = encode(payload)
// active;b;true|age;n;27|createdAt;d;"2025-12-29T10:00:00.000Z"|deletedAt;x;|name;s;"Yanto Kopling"|score;n;

Notes:

• Keys are sorted lexicographically to ensure deterministic output
• undefined values are omitted during encoding
• Non-finite numbers (NaN, Infinity) keep the n alias but encode with an empty value
• null is encoded explicitly using the x alias

Decode

const decoded = decode(encoded)
/*
{
	name: 'Yanto Kopling',
	age: 27,
	score: null,
	active: true,
	createdAt: Date,
	deletedAt: null, 
}
*/

With schema (TypeScript-safe)

const typed = decodeWithSchema(encoded, {
	name: 's',
	age: 'n',
	score: 'n',
	active: 'b',
	createdAt: 'd'
} as const)

/*
typed is inferred as:
{
  name: string
  age: number | null
  score: number | null
  active: boolean
  createdAt: Date
}
*/

Notes:

• undefined keys are omitted during encoding
• non-finite numbers (NaN, Infinity) keep alias n and decode to null
• output is deterministic (sorted keys, stable format)