Helper Functions for Dev.to RSS Integration

helper-functions.ts

// 1. Sanitize XML special characters
export function escapeXml(str: string): string {
  return str
    .replace(/&/g, "&")
    .replace(/</g, "&lt;")
    .replace(/>/g, "&gt;")
    .replace(/"/g, "&quot;")
    .replace(/'/g, "&apos;")
}

// 2. Escape CDATA closing tags
export function escapeCdata(str: string): string {
  return str.replace(/]]>/g, "]]]]><![CDATA[>")
}

// 3. Format tags for DEV.to (Alphanumeric only, max 20 chars, max 4 tags)
export function formatDevTags(rawTags: string[]): string[] {
  const seen = new Set<string>()
  const result: string[] = []

  for (const raw of rawTags) {
    const clean = raw.replace(/[^a-zA-Z0-9]/g, "").slice(0, 20)
    const key = clean.toLowerCase()
    if (!clean || seen.has(key)) continue
    seen.add(key)
    result.push(clean)
    if (result.length === 4) break
  }
  return result
}

// 4. Convert all relative URLs (src, href, srcset) to absolute URLs
export function makeUrlsAbsolute(html: string, baseUrl: string): string {
  return html.replace(/<[a-zA-Z][^<>]*>/g, (tag) =>
    tag
      .replace(
        /\b(href|src)="(\/[^"]*)"/g,
        (_, attr, val) => `${attr}="${new URL(val, baseUrl).toString()}"`
      )
      .replace(
        /\bsrcset="([^"]*)"/g,
        (_, val) => `srcset="${val.replace(/\/[^\s,]*/g, (p) => new URL(p, baseUrl).toString())}"`
      )
  )
}