netdisk-fast-download/IMPLEMENTATION_SUMMARY.md

Implementation Summary

Overview

Successfully implemented the backend portion of a browser-based TypeScript compilation solution for the netdisk-fast-download project. This implementation provides standard fetch API and Promise polyfills for the ES5 JavaScript engine (Nashorn), enabling modern JavaScript patterns in a legacy execution environment.

What Was Implemented

1. Promise Polyfill (ES5 Compatible)

File: parser/src/main/resources/fetch-runtime.js

A complete Promise/A+ implementation that runs in ES5 environments:

• ✅ new Promise(executor) constructor
• ✅ promise.then(onFulfilled, onRejected) with chaining
• ✅ promise.catch(onRejected) error handling
• ✅ promise.finally(onFinally) cleanup
• ✅ Promise.resolve(value) static method
• ✅ Promise.reject(reason) static method
• ✅ Promise.all(promises) parallel execution
• ✅ Promise.race(promises) with correct edge case handling

Key Features:

• Pure ES5 syntax (no ES6+ features)
• Uses setTimeout(fn, 0) for async execution
• Handles Promise chaining and nesting
• Proper error propagation

2. Fetch API Polyfill

File: parser/src/main/resources/fetch-runtime.js

Standard fetch API implementation that bridges to JsHttpClient:

• ✅ All HTTP methods: GET, POST, PUT, DELETE, PATCH, HEAD
• ✅ Request options: method, headers, body
• ✅ Response object with:
  • text() - returns Promise
  • json() - returns Promise