Merge pull request #16 from github/layout-table

Prevent parsing table[data-paste-markdown-skip]

Author: muan

README.md

@@ -1,7 +1,8 @@
 # Paste Markdown objects
 
-Paste spreadsheet cells as a Markdown table. Convert pasted image URLs to
-Markdown image link syntax.
+- Paste spreadsheet cells and HTML tables as a Markdown tables.
+- Paste image URLs as Markdown image links.
+- *Paste markdown as markdown. See [`@github/quote-selection`/Preserving markdown syntax](https://github.com/github/quote-selection/tree/9ae5f88f5bc3021f51d2dc9981eca83ce7cfe04f#preserving-markdown-syntax) for details.
 
 ## Installation
 
@@ -31,6 +32,16 @@ import subscribe from '@github/paste-markdown'
 observe('textarea[data-paste-markdown]', {subscribe})
 ```
 
+### Excluding `<table>`s
+
+Some `<table>`s are not meant to be pasted as markdown; for example, a file content table with line numbers in a column. Use `data-paste-markdown-skip` to prevent it.
+
+```html
+<table data-paste-markdown-skip>
+  ...
+</table>
+```
+
 ## Development
 
 ```

examples/index.html

@@ -29,7 +29,7 @@
     </tbody>
   </table>
 
-  <table border="1" cellpadding="5" class="js-comment">
+  <table border="1" cellpadding="5" data-paste-markdown-skip>
     <thead>
       <tr>
         <th>name</th>

src/paste-markdown-table.ts

@@ -95,17 +95,12 @@ function parseTable(html: string): HTMLElement | null {
   return el.querySelector('table')
 }
 
-function hasTable(transfer: DataTransfer): HTMLElement | null | void {
-  if (Array.from(transfer.types).indexOf('text/html') === -1) return
+function hasTable(transfer: DataTransfer): HTMLElement | null {
+  if (Array.from(transfer.types).indexOf('text/html') === -1) return null
 
   const html = transfer.getData('text/html')
-  if (!/<table/i.test(html)) return
+  if (!/<table/i.test(html)) return null
 
   const table = parseTable(html)
-  if (!table) return
-
-  // Edge copies the surrounding table from our issue comment text.
-  if (table.closest('.js-comment')) return
-
-  return /\b(js|blob|diff)-./.test(table.className) ? null : table
+  return !table || table.closest('[data-paste-markdown-skip]') ? null : table
 }

test/test.js

@@ -38,10 +38,10 @@ describe('paste-markdown', function() {
       assert.include(textarea.value, 'name | origin\n-- | --\nhubot | github\nbender | futurama')
     })
 
-    it('rejects HTML from github.com markup', function() {
+    it('rejects layout tables', function() {
       const data = {
         'text/html': `
-        <table class="js-comment">
+        <table data-paste-markdown-skip>
           <thead><tr><th>name</th><th>origin</th></tr></thead>
           <tbody>
             <tr><td>hubot</td><td>github</td></tr>