Feedscout

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Customize URL Resolution ​

Feedscout resolves discovered URLs before validation to ensure consistent results. You can provide a custom resolution function to change this behavior.

Default Behavior ​

By default, Feedscout resolves relative URLs against the base URL:

typescript
// Base URL: https://example.com/blog/
// Discovered: /feed.xml
// Resolved: https://example.com/feed.xml

// Base URL: https://example.com/blog/
// Discovered: ../rss
// Resolved: https://example.com/rss

Custom Resolution ​

Provide a resolveUrlFn to customize URL resolution:

typescript
import type { DiscoverResolveUrlFn } from 'feedscout'

const customResolve: DiscoverResolveUrlFn = (url, baseUrl) => {
  // Resolve relative URLs
  const resolved = new URL(url, baseUrl).href

  // Remove tracking parameters
  const parsed = new URL(resolved)
  parsed.searchParams.delete('utm_source')
  parsed.searchParams.delete('utm_medium')
  parsed.searchParams.delete('utm_campaign')

  return parsed.href
}

const feeds = await discoverFeeds(url, {
  methods: ['html', 'guess'],
  resolveUrlFn: customResolve,
})

// Also works with discoverHubs
const hubs = await discoverHubs(url, {
  resolveUrlFn: customResolve,
})

Interface ​

typescript
type DiscoverResolveUrlFn = (url: string, baseUrl: string | undefined) => string

Use Cases ​

Removing Query Parameters ​

Strip unnecessary query parameters:

typescript
const resolveUrl: DiscoverResolveUrlFn = (url, baseUrl) => {
  const resolved = new URL(url, baseUrl)

  // Keep only essential parameters
  const essentialParams = ['format', 'type']
  const params = new URLSearchParams()

  for (const key of essentialParams) {
    const value = resolved.searchParams.get(key)
    if (value) params.set(key, value)
  }

  resolved.search = params.toString()
  return resolved.href
}

Forcing HTTPS ​

Upgrade HTTP URLs to HTTPS:

typescript
const resolveUrl: DiscoverResolveUrlFn = (url, baseUrl) => {
  const resolved = new URL(url, baseUrl)
  resolved.protocol = 'https:'
  return resolved.href
}

Removing Trailing Slashes ​

Remove trailing slashes from paths:

typescript
const resolveUrl: DiscoverResolveUrlFn = (url, baseUrl) => {
  const resolved = new URL(url, baseUrl)
  resolved.pathname = resolved.pathname.replace(/\/+$/, '')
  return resolved.href
}

Custom Domain Handling ​

Rewrite URLs for specific domains:

typescript
const resolveUrl: DiscoverResolveUrlFn = (url, baseUrl) => {
  const resolved = new URL(url, baseUrl)

  // Use feeds subdomain for specific sites
  if (resolved.hostname === 'example.com') {
    resolved.hostname = 'feeds.example.com'
  }

  return resolved.href
}

Combining with Other Options ​

URL resolution works with discoverFeeds, discoverBlogrolls, and discoverHubs:

typescript
const feeds = await discoverFeeds(url, {
  methods: ['html', 'guess'],
  resolveUrlFn: customResolve,
  extractFn: customExtractor,
  concurrency: 3,
})

const hubs = await discoverHubs(url, {
  methods: ['headers', 'html'],
  resolveUrlFn: customResolve,
})