tslib-stdin

A Python-inspired, type-safe, synchronous standard input utility for TypeScript/Node.js.

Stop wrestling with asynchronous readline or callbacks just to get simple user input. tslib-stdin allows you to handle CLI inputs synchronously, with powerful type inference and object mapping.

Features

• 🚀 Synchronous Execution: Works just like Python's input().
• 🛡️ Type Safety: Automatic type inference for strings, numbers, and booleans.
• 🧩 Object Schema Mapping: Input multiple fields at once using a schema and rules.
• 📦 Zero Dependencies: Purely built on Node.js fs and buffer.
• 🛠️ Flexible Splitting: inputs() handles multiple delimiters (space, comma, semicolon, pipe, etc.).

Installation

npm install tslib-stdin

Quick Start

1. Basic Input

import { Stdin } from "tslib-stdin";

const name = Stdin.input("What is your name? ");
console.log(`Hello, ${name}!`);

2. Array Inputs (Split by delimiters)

Supports spaces, commas, tabs, pipes, and semicolons by default.

// User Input: 10, 20, 30
const [a, b, c] = Stdin.inputs("Enter three numbers: ", Number);
console.log(a + b + c); // 60 (as number)

3. Object Schema with Strict Rules

Map multiple inputs to an object. You can use built-in constructors (Number, String) or custom transform functions for Union Types.

type Rank = "Lv1" | "Lv2" | "Lv3";

const user = Stdin.object(
  {
    id: "Employee ID",
    name: "Full Name",
    rank: "Access Level",
  },
  {
    id: Number,
    name: String,
    rank: (v) => v as Rank, // Custom transform for Union Types
  },
);

// Fully typed!
console.log(user.id); // number
console.log(user.rank); // "Lv1" | "Lv2" | "Lv3"

API Reference

Stdin.input(prompt: string): string

Reads a single line from stdin.

Stdin.inputs<T>(prompt: string, parser?: (v: string) => T): T[]

Reads a line and splits it into an array.

• Default delimiters: , ; \t | and whitespace.
• If parser is provided (e.g., Number), it maps each element.

Stdin.object(schema, rule, promptFunc?)

Collects multiple inputs based on the schema.

• schema: { key: label }. The label is used for the prompt display.
• rule: { key: TransformFunc }. Must match the keys in schema.
• promptFunc: Optional. Customize how the prompt is displayed.
  • Default: (key) => ${key}:

License

MIT

MIT License

Copyright (c) 2026 JustifyBaby

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
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copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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SOFTWARE.