License Plate

Utilities for working with Indonesian Vehicle License Plates (Tanda Nomor Kendaraan Bermotor - TNKB).

Overview

The Plate module provides utilities to validate Indonesian license plates, detect the region/city based on the prefix, and format plates for consistent display.

Features

Validation: Check if a license plate follows the standard Indonesian format (1-2 letters prefix, 1-4 digits, and 1-3 letters suffix).
Region Detection: Identify the province or city associated with the plate’s prefix (e.g., ‘B’ for Jakarta, ‘D’ for Bandung).
Formatting: Normalize plate strings by removing extra spaces and ensuring the standard [PREFIX] [NUMBER] [SUFFIX] format.

Installation

npm


npm install @indodev/toolkit

pnpm


pnpm add @indodev/toolkit

yarn


yarn add @indodev/toolkit

bun


bun add @indodev/toolkit

Quick Start


import { validatePlate, getRegionFromPlate, formatPlate, parsePlate, maskPlate, cleanPlate, isPrivatePlate, isPublicPlate, isDiplomatPlate } from '@indodev/toolkit/plate';
 
// Validate Plate
validatePlate('B 1234 ABC'); // true
 
// Get Region
getRegionFromPlate('B 1234 ABC');
// 'DKI Jakarta, Tangerang, Bekasi, Depok'
 
getRegionFromPlate('D 1');
// 'Bandung, Cimahi'
 
// Format Plate
formatPlate('b1234abc');
// 'B 1234 ABC'
 
// Parse Plate
const info = parsePlate('B 1234 ABC');
console.log(info.prefix); // 'B'
console.log(info.number); // '1234'
console.log(info.suffix); // 'ABC'
console.log(info.type); // 'private'
 
// Mask Plate (for privacy)
maskPlate('B 1234 ABC'); // 'B****ABC'
 
// Clean Plate (remove non-alphanumeric)
cleanPlate('B 1234 ABC'); // 'B1234ABC'
 
// Check plate type
isPrivatePlate('B 1234 ABC');  // true
isPublicPlate('B 1234 U');    // false (single suffix treated as private)
isDiplomatPlate('CD 1234 AB'); // true

API Reference

validatePlate()

Validates if a string follows the Indonesian license plate format.

Type Signature:


function validatePlate(plate: string): boolean;

Parameters:

Name	Type	Description
`plate`	`string`	The license plate to validate

Returns:

boolean - Returns true if valid, false otherwise.

getRegionFromPlate()

Returns the region name(s) associated with a license plate’s prefix.

Type Signature:


function getRegionFromPlate(plate: string): string | null;

Parameters:

Name	Type	Description
`plate`	`string`	The license plate

Returns:

string | null - Region description, or null if the prefix is not recognized.

formatPlate()

Formats a license plate string into standard [PREFIX] [NUMBER] [SUFFIX] format.

Type Signature:


function formatPlate(plate: string): string;

Parameters:

Name	Type	Description
`plate`	`string`	The license plate text

Returns:

string - Formatted license plate, or the original if invalid.

parsePlate()

Parses a license plate and extracts its component parts.

Type Signature:


function parsePlate(plate: string): PlateInfo | null;

Parameters:

Name	Type	Description
`plate`	`string`	The license plate to parse

Returns:

PlateInfo | null - Parsed plate information or null if invalid.

Example:


const info = parsePlate('B 1234 ABC');
if (info) {
  console.log(info.prefix); // 'B'
  console.log(info.number); // '1234'
  console.log(info.suffix); // 'ABC'
  console.log(info.type); // 'private'
  console.log(info.formatted); // 'B 1234 ABC'
  console.log(info.isValid); // true
}
 
// Parse diplomat plate
const diplomat = parsePlate('CD 1234 AB');
console.log(diplomat?.type); // 'diplomat'

maskPlate()

Masks a license plate number for privacy.

Type Signature:


function maskPlate(plate: string, options?: PlateMaskOptions): string;

Parameters:

Name	Type	Description
`plate`	`string`	The license plate to mask
`options`	`PlateMaskOptions`	Optional masking configuration

Returns:

string - Masked plate string (without spaces), or empty string if invalid.

Example:


maskPlate('B 1234 ABC'); // 'B****ABC'
maskPlate('B 1234 ABC', { visibleStart: 2 }); // 'B1***ABC'
maskPlate('B 1234 ABC', { maskChar: '#' }); // 'B####ABC'

cleanPlate()

Cleans a license plate by removing all non-alphanumeric characters.

Type Signature:


function cleanPlate(plate: string): string;

Parameters:

Name	Type	Description
`plate`	`string`	The license plate to clean

Returns:

string - Cleaned plate string (alphanumeric only, uppercase).

Example:


cleanPlate('B 1234 ABC');  // 'B1234ABC'
cleanPlate('da-1234-xyz'); // 'DA1234XYZ'

isPrivatePlate()

Checks if a license plate is a private vehicle plate.

Type Signature:


function isPrivatePlate(plate: string): boolean;

Parameters:

Name	Type	Description
`plate`	`string`	The license plate to check

Returns:

boolean - Returns true if valid private plate, false otherwise.

isPublicPlate()

Checks if a license plate is a public transportation plate.

Type Signature:


function isPublicPlate(plate: string): boolean;

Parameters:

Name	Type	Description
`plate`	`string`	The license plate to check

Returns:

boolean - Returns true if valid public plate, false otherwise.

isDiplomatPlate()

Checks if a license plate is a diplomat plate.

Type Signature:


function isDiplomatPlate(plate: string): boolean;

Parameters:

Name	Type	Description
`plate`	`string`	The license plate to check

Returns:

boolean - Returns true if valid diplomat plate, false otherwise.

Constants

PLATE_REGIONS

A mapping of license plate prefixes to their respective regions.


import { PLATE_REGIONS } from '@indodev/toolkit/plate';
 
console.log(PLATE_REGIONS['B']); // 'DKI Jakarta, Tangerang, Bekasi, Depok'
console.log(PLATE_REGIONS['D']); // 'Bandung, Cimahi'

PlateInfo

Information extracted from a valid license plate.


interface PlateInfo {
  prefix: string;      // Plate prefix (e.g., 'B')
  number: string;       // Plate number (e.g., '1234')
  suffix: string;       // Plate suffix (e.g., 'ABC')
  type: 'private' | 'public' | 'diplomat' | null;
  formatted: string;     // Formatted plate (e.g., 'B 1234 ABC')
  isValid: boolean;     // Whether the plate passed validation
}

PlateMaskOptions

Options for masking a license plate.


interface PlateMaskOptions {
  visibleStart?: number; // Characters visible at start (default: 1)
  visibleEnd?: number;   // Characters visible at end (default: 3)
  maskChar?: string;     // Mask character (default: '*')
}

InvalidPlateError

Error class for invalid plate with error code for programmatic handling.


class InvalidPlateError extends Error {
  readonly code = 'INVALID_PLATE';
  constructor(message?: string);
}

Example:


import { InvalidPlateError, validatePlate } from '@indodev/toolkit/plate';
 
try {
  if (!validatePlate(plate)) {
    throw new InvalidPlateError('Invalid plate format');
  }
} catch (error) {
  if (error instanceof InvalidPlateError) {
    console.log(error.code); // 'INVALID_PLATE'
  }
}