searchText.js

// Run a batch operation against the Word object model.
Word.run(function (context) {

    // Queue a command to search the document with a case insensitive search.
    var searchResults = context.document.body.search('video', {matchCase: false});

    // 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-up 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 = '#FF0000'; //Red
            searchResults.items[i].font.highlightColor = '#FFFF00'; //Yellow
            searchResults.items[i].font.bold = true;
        }
        
        // Synchronize the document state by executing the queued-up 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));
    }
});