Cells pasted from clipboard's tables won't contain unnecessary line breaks

.changelogs/10745.json

@@ -0,0 +1,8 @@
+{
+  "issuesOrigin": "private",
+  "title": "Cells pasted from clipboard's tables won't contain unnecessary line breaks",
+  "type": "fixed",
+  "issueOrPR": 10745,
+  "breaking": false,
+  "framework": "none"
+}

handsontable/src/utils/__tests__/parseTable.unit.js

@@ -304,6 +304,75 @@ describe('htmlToGridSettings', () => {
     expect(config.mergeCells[1].rowspan).toBe(4);
   });
 
+  it('should parse table with long text properly', () => {
+    /* eslint-disable no-irregular-whitespace */
+    const htmlToParse = `
+      <table>
+       <tr>
+        <td>
+        <p><span>Some very long text with no line breaks inside table
+        cell. Some very long text with no line breaks</span></p>
+        <p><span>&nbsp;</span></p>
+        <p><span>&nbsp;</span></p>
+        <p><span>ins table cell. Some very long text with no line breaks
+        inside table cell. Some very long text with no line breaks inside table cell.
+        Some very long text with no line breaks inside table cell. Some very long
+        text with no line breaks inside table cell. Some very long text with no line
+        breaks inside table cell. Some very long text with no line breaks inside
+        table cell. Some very long text with no line breaks inside table cell. Some
+        very long text with no line breaks inside table cell. Some very long text
+        with no line breaks inside table cell. Some very long text with no line
+        breaks inside table cell. Some very long text with no line breaks inside
+        table cell. Some very long text with no line breaks inside table cell. Some
+        very long text with no line breaks inside table cell. Some very long text
+        with no line breaks inside table cell. Some very long text with no line
+        breaks inside table cell. Some very long text with no line breaks inside
+        table cell. Some very long text with no line breaks inside table cell. Some
+        very long text with no line breaks inside table cell. Some very long text
+        with no line breaks inside table cell. Some very long text with no line
+        breaks inside table cell. Some very long text with no line breaks inside
+        table cell. Some very long text with no line breaks inside table cell.</span></p>
+        </td>
+       </tr>
+       <tr>
+        <td>
+        <p><span>Another very long text with no line breaks inside table
+        cell. <span>       </span>Some very long text with
+        no line breaks <span>     </span>o line breo line
+        breo line breo line breo line bre</span></p>
+        <p><span>&nbsp;</span></p>
+        <p><span>NEW LINE</span></p>
+        </td>
+       </tr>
+      </table>`;
+    /* eslint-enable */
+
+    const config = htmlToGridSettings(htmlToParse);
+
+    expect(config.data).toEqual([[
+      'Some very long text with no line breaks inside table cell. Some very long text with no line breaks' +
+      '\n\n\n' +
+      'ins table cell. Some very long text with no line breaks inside table cell. Some very long text with no line ' +
+      'breaks inside table cell. Some very long text with no line breaks inside table cell. Some very long text with ' +
+      'no line breaks inside table cell. Some very long text with no line breaks inside table cell. Some very long ' +
+      'text with no line breaks inside table cell. Some very long text with no line breaks inside table cell. Some ' +
+      'very long text with no line breaks inside table cell. Some very long text with no line breaks inside table ' +
+      'cell. Some very long text with no line breaks inside table cell. Some very long text with no line breaks ' +
+      'inside table cell. Some very long text with no line breaks inside table cell. Some very long text with no ' +
+      'line breaks inside table cell. Some very long text with no line breaks inside table cell. Some very long ' +
+      'text with no line breaks inside table cell. Some very long text with no line breaks inside table cell. Some ' +
+      'very long text with no line breaks inside table cell. Some very long text with no line breaks inside table ' +
+      'cell. Some very long text with no line breaks inside table cell. Some very long text with no line breaks ' +
+      'inside table cell. Some very long text with no line breaks inside table cell. Some very long text with no ' +
+      'line breaks inside table cell.'
+    ], [
+      'Another very long text with no line breaks inside table cell.        Some very long text with no line ' +
+      'breaks      o line breo line breo line breo line breo line bre' +
+      '\n\n' +
+      'NEW LINE'
+    ]]);
+  });
+
   describe('nestedHeaders', () => {
     it('should parse nested headers from HTML table', () => {
       const htmlToParse = [

handsontable/src/utils/parseTable.js

@@ -171,8 +171,16 @@ export function htmlToGridSettings(element, rootDocument = document) {
   if (typeof checkElement === 'string') {
     const escapedAdjacentHTML = checkElement.replace(/<td\b[^>]*?>([\s\S]*?)<\/\s*td>/g, (cellFragment) => {
       const openingTag = cellFragment.match(/<td\b[^>]*?>/g)[0];
+      const paragraphRegexp = /<p.*?>/g;
       const cellValue = cellFragment
-        .substring(openingTag.length, cellFragment.lastIndexOf('<')).replace(/(<(?!br)([^>]+)>)/gi, '');
+        .substring(openingTag.length, cellFragment.lastIndexOf('<'))
+        .trim() // Removing whitespaces from the start and the end of HTML fragment
+        .replaceAll(/\n\s+/g, ' ') // HTML tags may be split using multiple new lines and whitespaces
+        .replaceAll(paragraphRegexp, '\n') // Only paragraphs should split text using new line characters
+        .replace('\n', '') // First paragraph shouldn't start with new line characters
+        .replaceAll(/<\/(.*)>\s+$/mg, '</$1>') // HTML tags may end with whitespace.
+        .replace(/(<(?!br)([^>]+)>)/gi, '') // Removing HTML tags
+        .replaceAll(/^&nbsp;$/mg, ''); // Removing single &nbsp; characters separating new lines
       const closingTag = '</td>';
 
       return `${openingTag}${cellValue}${closingTag}`;