feat(shared): add isLinkFtp util

Author: meteorlxy

packages/@vuepress/shared/__tests__/utils/isLinkFtp.spec.ts

@@ -0,0 +1,20 @@
+import { isLinkFtp } from '@vuepress/shared'
+
+const testCases: [string, ReturnType<typeof isLinkFtp>][] = [
+  ['ftp://foobar.com', true],
+  ['https://foobar.com', false],
+  ['http://foobar.com', false],
+  ['//foobar.com', false],
+  ['foobar.com', false],
+  ['/foo/bar', false],
+]
+
+describe('shared > isLinkFtp', () => {
+  describe('should determine ftp link correctly', () => {
+    testCases.forEach(([source, expected]) => {
+      it(`link: ${source}`, () => {
+        expect(isLinkFtp(source)).toBe(expected)
+      })
+    })
+  })
+})

packages/@vuepress/shared/src/utils/index.ts

@@ -7,6 +7,7 @@ export * from './formatDateString'
 export * from './htmlEscape'
 export * from './htmlUnescape'
 export * from './isLinkExternal'
+export * from './isLinkFtp'
 export * from './isLinkHttp'
 export * from './isLinkMailto'
 export * from './isLinkTel'

packages/@vuepress/shared/src/utils/isLinkFtp.ts

@@ -0,0 +1,4 @@
+/**
+ * Determine a link is ftp link or not
+ */
+export const isLinkFtp = (link: string): boolean => link.startsWith('ftp://')