fix: only markdownify if corresponding plaintext can be found

test: add test

Author: imjohnbo

src/paste-markdown-html.ts

@@ -13,10 +13,8 @@ type MarkdownTransformer = (element: HTMLElement | HTMLAnchorElement, args: stri
 function onPaste(event: ClipboardEvent) {
   const transfer = event.clipboardData
   // if there is no clipboard data, or
-  // if there is no html content in the clipboard, or
-  // if the browser has made an "improved URL for pasting", return
-  // See https://support.microsoft.com/en-gb/microsoft-edge/improved-copy-and-paste-of-urls-in-microsoft-edge-d3bd3956-603a-0033-1fbc-9588a30645b4 for more
-  if (!transfer || !hasHTML(transfer) || hasLinkPreview(transfer)) return
+  // if there is no html content in the clipboard, return
+  if (!transfer || !hasHTML(transfer)) return
 
   const field = event.currentTarget
   if (!(field instanceof HTMLTextAreaElement)) return
@@ -56,8 +54,10 @@ function transform(
   for (const element of elements) {
     const textContent = element.textContent || ''
     const {part, index} = trimAfter(text, textContent)
-    markdownParts.push(part.replace(textContent, transformer(element, args)))
-    text = text.slice(index)
+    if (index >= 0) {
+      markdownParts.push(part.replace(textContent, transformer(element, args)))
+      text = text.slice(index)
+    }
   }
   markdownParts.push(text)
   return markdownParts.join('')
@@ -83,10 +83,6 @@ function hasHTML(transfer: DataTransfer): boolean {
   return transfer.types.includes('text/html')
 }
 
-function hasLinkPreview(transfer: DataTransfer): boolean {
-  return transfer.types.includes('text/link-preview')
-}
-
 function linkify(element: HTMLAnchorElement): string {
   return `[${element.textContent}](${element.href})`
 }

test/test.js

@@ -147,6 +147,23 @@ describe('paste-markdown', function () {
       paste(textarea, {'text/html': sentence, 'text/plain': plaintextSentence})
       assert.equal(textarea.value, markdownSentence)
     })
+
+    it('doesn\'t render any markdown for html link without corresponding plaintext', function () {
+      // eslint-disable-next-line github/unescaped-html-literal
+      const link = `<meta charset='utf-8'><a href="https://github.com/monalisa/playground/issues/1">
+        Link pasting · Issue #1 · monalisa/playground (github.com)</a>`
+      const plaintextLink = 'https://github.com/monalisa/playground/issues/1'
+      const linkPreviewLink = {
+        domain: 'github.com',
+        preferred_format: 'text/html;content=titled-hyperlink',
+        title: 'Link pasting · Issue #1 · monalisa/playground (github.com)',
+        type: 'website',
+        url: 'https://github.com/monalisa/playground/issues/1'
+      }
+
+      paste(textarea, {'text/html': link, 'text/plain': plaintextLink, 'text/link-preview': linkPreviewLink})
+      assert.equal(textarea.value, '')
+    })
   })
 })