javascript-fwf

javascript-fwf is a fast, type-safe JavaScript / ES Module library for parsing, validating, and exporting Fixed Width Files (FWF).

It is part of the Fixed Width File Ecosystem and fully implements the fwf-compliance-tests v1.0.0 specification.

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🌟 Key Features

• Type-Safe Columns: CharColumn, RightCharColumn, PositiveIntegerColumn, PositiveDecimalColumn, DateColumn, TimeColumn, and DateTimeColumn.
• Flexible Descriptors: Structured records with HeaderRowDescriptor, DetailRowDescriptor, and FooterRowDescriptor.
• Multiple Output Renders: Export layout specifications to Markdown, ReStructuredText (RST), or HTML tables via RenderUtils.
• Full Test Suite & Compliance: 100% compliant with fwf-compliance-tests v1.0.0.
• Git Hooks Ready: Pre-configured pre-commit and pre-push hooks.

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🚀 Installation

Install via npm:

npm install @fixed-width-file/javascript-fwf

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💡 Quickstart

import {
  CharColumn,
  PositiveIntegerColumn,
  DetailRowDescriptor,
  FileDescriptor,
  Reader
} from '@fixed-width-file/javascript-fwf';

// 1. Define columns
const nameCol = new CharColumn('name', 20, 'User Name');
const ageCol = new PositiveIntegerColumn('age', 3, 'Age in years');

// 2. Define row and file descriptors
const detail = new DetailRowDescriptor([nameCol, ageCol]);
const fileDescriptor = new FileDescriptor([detail]);

// 3. Read fixed-width file content
const content = "KELSON MEDEIROS     045\nMARIA SILVA         030\n";
const reader = new Reader(content, fileDescriptor, "\n");

for (const row of reader) {
  console.log(`Name: ${row.name} | Age: ${row.age}`);
}

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🧪 Testing & Compliance

Run unit tests using Vitest:

npm test

Run test coverage:

npm run test:coverage

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⚓ Pre-Commit & Pre-Push Setup

Set up pre-commit and pre-push hooks:

pre-commit install
pre-commit install --hook-type pre-push

Run checks manually:

pre-commit run --all-files

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📄 License

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