make linksToSkip an async function

README.md

@@ -127,7 +127,7 @@ Asynchronous method that runs a site wide scan. Options come in the form of an o
 - `concurrency` (number) - The number of connections to make simultaneously. Defaults to 100.
 - `port` (number) - When the `path` is provided as a local path on disk, the `port` on which to start the temporary web server. Defaults to a random high range order port.
 - `recurse` (boolean) - By default, all scans are shallow. Only the top level links on the requested page will be scanned. By setting `recurse` to `true`, the crawler will follow all links on the page, and continue scanning links **on the same domain** for as long as it can go. Results are cached, so no worries about loops.
-- `linksToSkip` (array | function) - An array of regular expression strings that should be skipped, OR a function that's called for each link with the link URL as its only argument. Return `true` to skip the link or `false` to check it.
+- `linksToSkip` (array | function) - An array of regular expression strings that should be skipped, OR an async function that's called for each link with the link URL as its only argument. Return a Promise that resolves to `true` to skip the link or `false` to check it.
 
 #### linkinator.LinkChecker()
 Constructor method that can be used to create a new `LinkChecker` instance. This is particularly useful if you want to receive events as the crawler crawls. Exposes the following events:

src/index.ts

@@ -16,7 +16,7 @@ export interface CheckOptions {
  port?: number;
  path: string;
  recurse?: boolean;
- linksToSkip?: string[] | ((link: string) => boolean);
+ linksToSkip?: string[] | ((link: string) => Promise<boolean>);
 }
 
 export enum LinkState {
@@ -140,7 +140,7 @@ export class LinkChecker extends EventEmitter {
  // Check for a user-configured function to filter out links
  if (
  typeof opts.checkOptions.linksToSkip === 'function' &&
- opts.checkOptions.linksToSkip(opts.url.href)
+ (await opts.checkOptions.linksToSkip(opts.url.href))
  ) {
  const result: LinkResult = {
  url: opts.url.href,

test/test.ts

@@ -51,7 +51,7 @@ describe('linkinator', () => {
  .reply(200);
  const results = await check({
  path: 'test/fixtures/filter',
- linksToSkip: link => link.includes('filterme'),
+ linksToSkip: link => Promise.resolve(link.includes('filterme'))
  });
  assert.ok(results.passed);
  assert.strictEqual(