Get Started with the Document Compare Demo - HTML5 JavaScript

This tutorial shows how to configure and run the LEADTOOLS Document Compare Demo with the Document Service.

Summary This tutorial covers how to configure and run the LEADTOOLS Document Compare Demo with the Document Service.
Completion Time 5 - 10 minutes
Platform HTML5/JS
IDE Visual Studio 2017, 2019
Development License Download LEADTOOLS

Required Knowledge

Be sure to download and install the LEADTOOLS SDK, and make sure that your license and key files are located in your <INSTALL_DIR>\LEADTOOLS22\Support\Common\License directory.

Open the Document Compare Demo

The installed LEADTOOLS SDK enables an HTML5/JavaScript Document Compare Demo which showcases many of the features that the SDK offers.

Once the LEADTOOLS SDK is installed, using File Explorer, navigate to the demo in the file path below:


Set up and Configure the Demo with the Document Service

The Document Compare Demo relies on a server-side backend service for some of its functionality:

The Document Service is written in 3 different languages. Each Document Service uses a different Port when deploying, by default.

Language Path to Service Project Default Url Compatible OS
.NET Framework <INSTALL_DIR>\LEADTOOLS22\Examples\Document\JS\DocumentServiceDotNet\fx http://localhost:40000/ Windows
.NET Core <INSTALL_DIR>\LEADTOOLS22\Examples\Document\JS\DocumentServiceDotNet\net http://localhost:30000/ Windows, Linux, Mac
Java <INSTALL_DIR>\LEADTOOLS22\Examples\Document\JS\DocumentServiceJava http://localhost:8080/ Windows, Linux, Mac

By default, the Document Compare Demo is configured to work with the .NET Framework service. To change the URL to work with another service URL, simply open <INSTALL_DIR>\LEADTOOLS22\Examples\Viewers\JS\DocumentCompareDemo\static\config.json and modify the serviceHost value to the correct URL:

   "serviceHost": "http://localhost:40000", 
   "servicePath": "", 
   "serviceApiPath": "api", 

Run the .NET Framework Document Service

The .NET Framework Document Service has 2 different projects that can be opened. The DocumentService.csproj uses local references from <INSTALL_DIR>\LEADTOOLS22\Bin\Dotnet4\<CPU_ARCH>, and the DocumentService_Nuget.csproj uses NuGet Packages. Choose one, and open it in Visual Studio.

Run the project through Visual Studio and explore the resources and options already available. Decide on the type of project to compile, and whether to use the NuGet Packages.

Run the .NET Core Document Service

The .NET Core Document Service DocumentService.csproj uses NuGet Packages. This project can be built and run on any operating system that has .NET Core installed on it. It can be run through Visual Studio on Windows via IIS Express.

When running on Linux or outside of Visual Studio, run dotnet publish from the development environment to package the application into a directory (for example, bin\Debug\netcoreapp2.1\publish). Copy the new publish directory to the machine in the desired location, then test the application using dotnet DocumentService.dll and browse to the URL.

Run the Java Document Service

To set up the Java Environment for use with the LEADTOOLS Document Service, refer to the PDF located here: <INSTALL_DIR>\LEADTOOLS22\Examples\Document\JS\Services\Help\JavaDocumentViewerSetup.pdf

Run the Document Compare Demo with a Service

Open a Command Prompt window and cd into the Document Compare Demo folder in the file path below:


Next, run npm install to pull in project dependencies.

Create a new folder in the ./static directory labeled LT and copy all the LEADTOOLS javascript files in the <INSTALL_DIR>\LEADTOOLS22\Bin\JS\ including inside the DemoLibraries and ThirdParty folders to the new directory of ./static/LT.

Include a batch script to copy all the LEADTOOLS dependency files by running npm run update in the Command Prompt.

Now that the Document Service is running and the Document Compare Demo is properly set up to use the URL in the config.json file as described in the steps above, run the Document Compare Demo via the Command Prompt with npm run start.

Note To build a deployable version of the demo use npm run build and the ./static directory will contain a shippable version of the demo which could be placed in IIS or another designated web server.

When the demo launches, it will connect to the service and load a default PDF. If there are any issues during the setup, this is typically where they will appear.


If the Document Service is not running when launching the Document Compare Demo, a dialog will open in the browser with the message Cannot reach the LEADTOOLS Document Service. Retry the steps above to verify the Document Compare Demo is using the correct URL and that the service is actively running. If both are set up correctly, check the Console in the Browse Dev Tools (F12) for any errors listed.

Load Documents to Compare

Once everything is set up and the default PDF is loaded into the viewer, other documents and images can now be loaded via the File menu. There are 3 different methods of loading a document:

Dialog menu of the 3 different methods:

There are 3 different methods of loading a document

The following table describes the 3 methods:

Menu Item Description
Open local file Open a local file from the client system
Open from URL Open a file from a URL
Open from cache Open a file that has been saved to the Document Viewer cache on the server

Start the Compare

When the Documents are ready to be compared, selecting the triangle in the "Text Compare" will alert and ask to begin the compare.

Start Compare of documents

The Document Compare Demo is able to additionally compare the raster images. Use the second from the right icon in the Text Compare panel to toggle to the Raster Compare panel.

Generate a Report

The Document Compare Demo is able to generate a markdown (.MD) file with all the changes that occur and can be downloaded using the Save button that is located next to the Start Compare triangle button mentioned previously.


This tutorial showed how to connect and configure the LEADTOOLS Document Compare Demo to the Document Service and how to load documents, compare document, and export a comparison report. We also covered how to modify the settings on both the client-side and server-side.

See Also

Help Version 22.0.2024.3.20
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© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.

Products | Support | Contact Us | Intellectual Property Notices
© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.