LEI Validator

A robust JavaScript library for validating Legal Entity Identifiers (LEIs) according to the ISO 17442 standard.

Features

• ✅ Complete LEI validation according to ISO 17442
• 🔍 Detailed error reporting
• 🧩 LEI component breakdown
• 🔢 Check digit generation
• 💪 TypeScript-friendly with JSDoc annotations

Installation

<script src="//cdn.jsdelivr.net/gh/mczen-technologies/lei-validator@latest/index.js"></script>

Usage

Basic Validation

const validator = new LEIValidator("213800D1L3R2MWV39G88");
const isValid = validator.isValid();

console.log(isValid ? "Valid LEI" : "Invalid LEI");

Detailed Validation with Error Messages

const validator = new LEIValidator("213800D1L3R2MWV39G88");
const result = validator.validate();

if (result.isValid) {
    console.log("Valid LEI");
} else {
    console.log("Invalid LEI:", result.errors);
}

Get LEI Components

const validator = new LEIValidator("213800D1L3R2MWV39G88");
const parts = validator.getParts();

console.log(parts);
// Output:
// {
//     louPrefix: "2138",
//     entityPart: "00D1L3R2MWV39G",
//     checkDigits: "88"
// }

Generate Check Digits

const checkDigits = LEIValidator.generateCheckDigits("213800D1L3R2MWV39G");
console.log("Check digits:", checkDigits);

LEI Structure

An LEI is a 20-character identifier that consists of:

1. LOU Prefix (Characters 1-4):

   • Identifies the Local Operating Unit that issued the LEI
   • Alphanumeric characters only

2. Entity-Specific Part (Characters 5-18):

   • Unique to the entity
   • Alphanumeric characters only

3. Check Digits (Characters 19-20):

   • Two numeric characters
   • Calculated using ISO 17442 algorithm

Validation Rules

The validator checks:

• Length (must be exactly 20 characters)
• Character set (uppercase alphanumeric only)
• LOU prefix format
• Entity-specific part format
• Check digits using MOD 97-10 algorithm

API Reference

Class: LEIValidator

Constructor

const validator = new LEIValidator(lei: string)

Throws TypeError if the input is not a string.

Methods

isValid(): boolean

Returns whether the LEI is valid.

validate(): ValidationResult

Returns detailed validation results.

interface ValidationResult {
    isValid: boolean;
    errors: string[];
}

getParts(): Object

Returns the components of the LEI.

{
    louPrefix: string;
    entityPart: string;
    checkDigits: string;
}

static generateCheckDigits(partialLei: string): string

Generates valid check digits for a partial LEI (first 18 characters).

Error Handling

The validator provides detailed error messages for:

• Invalid input types
• Incorrect length
• Invalid characters
• Invalid LOU prefix
• Invalid entity-specific part
• Invalid check digits

Contributing

1. Fork the repository
2. Create your feature branch (git checkout -b feature/AmazingFeature)
3. Commit your changes (git commit -m 'Add some AmazingFeature')
4. Push to the branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

License

This project is licensed under the MIT License - see the LICENSE file for details.

Author

McZEN Technologies

Acknowledgments

• ISO 17442 standard for LEI structure
• GLEIF (Global Legal Entity Identifier Foundation) for LEI specifications

Change Log

Version 1.0.0

• Initial release
• Basic LEI validation
• Component breakdown
• Check digit generation
• Detailed error reporting