Open External Links in New Tabs

Add target="_blank" to links pointing to other websites.

Overview

Markdown gives you no control over how a link opens: [Saga](https://github.com/loopwerk/Saga) always becomes a plain <a href="...">. Since item processors run after the reader has turned Markdown into HTML, you can rewrite those links before they’re written to disk.

SagaUtils ships a processExternalLinks transformation that does exactly this: every link whose href starts with http:// or https:// gets target="_blank" and rel="noopener".

Setup

Add SagaUtils to your Package.swift:

.package(url: "https://github.com/loopwerk/SagaUtils", from: "1.0.0"),

Register the processor

SagaUtils’ transformations are combined with swiftSoupProcessor, which parses the item’s body once, applies each transformation in order, and serializes it back:

import SagaUtils

try await Saga(input: "content", output: "deploy")
  .register(
    folder: "articles",
    metadata: ArticleMetadata.self,
    readers: [.parsleyMarkdownReader],
    itemProcessor: swiftSoupProcessor(processExternalLinks),
    writers: [.itemWriter(swim(renderArticle))]
  )
  .run()

Relative links like /articles/my-first-article/ are left alone. If you link to your own site with absolute URLs, those are treated as external too. See below for how to exclude your own domain.

Combining with other processors

To mix this with other processors, use sequence(_:):

let articleProcessor = sequence(
  swiftSoupProcessor(convertAsides, processExternalLinks),
  publicationDateInFilename
)

Writing your own version

processExternalLinks is deliberately simple. If you want different rel values, or you link to your own site with absolute URLs and don’t want those to open in a new tab, write your own transformation. Any (Document, Item<M>) throws -> Void function can be passed to swiftSoupProcessor:

import SagaUtils
import SwiftSoup

func openExternalLinksInNewTab<M>(_ doc: Document, item: Item<M>) throws {
  for link in try doc.select("a[href]") {
    let href = try link.attr("href")
    guard let host = URL(string: href)?.host, host != "www.example.com" else {
      continue
    }
    try _ = link.attr("target", "_blank")
    try _ = link.attr("rel", "noopener")
  }
}

Relative links have no host, so they’re skipped by the guard.