Search and highlight text using word add-in

 // Run a batch operation against the Word object model.
Word.run(function (context) {
  // Queue a command to search the document and ignore punctuation.
  var searchResults = context.document.body.search('Office', {ignorePunct: true});

  // Queue a command to load the search results and get the font property values.
  context.load(searchResults, 'font');

  // Synchronize the document state by executing the queued commands,
  // and return a promise to indicate task completion.
  return context.sync().then(function () {
      console.log('Found count: ' + searchResults.items.length);

      // Queue a set of commands to change the font for each found item.
      for (var i = 0; i < searchResults.items.length; i++) {
        searchResults.items[i].font.color = 'purple';
        searchResults.items[i].font.highlightColor = '#FFFF00'; // Yellow
        searchResults.items[i].font.bold = true;
      }

      // Synchronize the document state by executing the queued commands,
      // and return a promise to indicate task completion.
      return context.sync();
  });
})
.catch(function (error) {
  console.log('Error: ' + JSON.stringify(error));
  if (error instanceof OfficeExtension.Error) {
    console.log('Debug info: ' + JSON.stringify(error.debugInfo));
  }
});