JavaScript Client Library¶

Modern JavaScript/Node.js client for the Danish Parliament API with fetch-based examples, async patterns, and browser support.

Features¶

Modern ES6+: Uses fetch API and async/await
Browser & Node.js: Works in both environments
Generator Patterns: Memory-efficient pagination
Error Handling: Comprehensive error management
TypeScript Ready: Full type support available
No Dependencies: Uses native fetch API

Quick Start¶

// ES6 Modules
import { DanishParliamentAPI } from './danish-parliament-api.js';

// CommonJS (Node.js)
const { DanishParliamentAPI } = require('./danish-parliament-api.js');

// Initialize client
const api = new DanishParliamentAPI();

// Get recent cases
const cases = await api.getCases({ top: 10 });
console.log(`Found ${cases.value.length} cases`);

// Search for climate legislation
const climateCases = await api.getCases({
  filter: "substringof('klima', titel)",
  top: 50
});
console.log(`Climate cases: ${climateCases.value.length}`);

Installation¶

Browser (ES6 Modules)¶

<script type="module">
import { DanishParliamentAPI } from './js/danish-parliament-api.js';

const api = new DanishParliamentAPI();
// Use the API...
</script>

Node.js¶

# No installation needed - uses native fetch (Node.js 18+)
# For older Node.js versions:
npm install node-fetch

Client Libraries¶

Fetch Client - Complete modern client implementation
Pagination - Generator patterns for large datasets
Browser Usage - Client-side usage and CORS handling

Examples¶

Parliamentary Monitoring¶

// Monitor recent activity
const recentChanges = await api.getRecentChanges('Sag', 4); // Last 4 hours
for (const case of recentChanges.value) {
  console.log(`Updated: ${case.titel} at ${case.opdateringsdato}`);
}

Voting Analysis¶

// Get all votes by a politician
const votes = await api.getVotingRecords('Frank Aaen');
console.log(`Found ${votes.length} votes`);

// Analyze voting patterns
const voteAnalysis = api.analyzeVotingPatterns(votes);
console.log(voteAnalysis);

Concurrent Processing¶

// Process multiple search terms concurrently
const searchTerms = ['klima', 'miljø', 'energi'];
const results = await Promise.all(
  searchTerms.map(term => 
    api.getCases({ filter: `substringof('${term}', titel)` })
  )
);

searchTerms.forEach((term, i) => {
  console.log(`${term}: ${results[i].value.length} cases`);
});

Browser Compatibility¶

Modern browsers: Chrome 42+, Firefox 39+, Safari 10.1+, Edge 14+
Node.js: 18+ (native fetch) or 14+ with node-fetch polyfill
CORS: API supports cross-origin requests from browsers

Key Features¶

1. Modern JavaScript¶

Uses native fetch() API
Async/await throughout
ES6 classes and modules
Promise-based error handling

2. Efficient Pagination¶

Generator functions for memory efficiency
Automatic batching and rate limiting
Progress tracking and resumption

3. Error Handling¶

Comprehensive error classification
Automatic retry with exponential backoff
Network error recovery

4. Performance Optimized¶

Connection reuse
Request deduplication
Intelligent caching
Concurrent request limiting

Usage Patterns¶

Simple Queries¶

// Get basic case information
const cases = await api.getCases({ top: 20 });

// Search with filters
const filtered = await api.getCases({
  filter: "year(opdateringsdato) eq 2025",
  orderby: "opdateringsdato desc"
});

Advanced Queries¶

// Complex relationships
const casesWithActors = await api.getCases({
  expand: "SagAktør/Aktør",
  filter: "substringof('klima', titel)",
  select: "id,titel,SagAktør/Aktør/navn"
});

// Multiple entity queries
const [cases, actors, votes] = await Promise.all([
  api.getCases({ top: 10 }),
  api.getActors({ top: 10 }), 
  api.getVotingSessions({ top: 5 })
]);

Streaming Data¶

// Process large datasets efficiently
for await (const case of api.paginateAll('Sag', { batchSize: 100 })) {
  // Process each case individually
  console.log(case.titel);

  // Memory stays constant even for 100k+ records
}

Error Handling¶

try {
  const cases = await api.getCases({ top: 10 });
  console.log(`Success: ${cases.value.length} cases`);
} catch (error) {
  if (error.name === 'ValidationError') {
    console.error('Invalid parameters:', error.message);
  } else if (error.name === 'NetworkError') {
    console.error('Network issue:', error.message);
  } else if (error.name === 'APIError') {
    console.error('API error:', error.message);
  } else {
    console.error('Unexpected error:', error);
  }
}

Next Steps¶

Fetch Client - Complete implementation
Pagination - Handle large datasets
Browser Usage - Client-side patterns