What is the best practice for testing the web applications where all processing happen on client side? using what tools and which approach? We used selenium plugin on jmeter for one of the projects but we realized that it might not be the correct way to measure the performance.
If the processing is happening purely on the client side the only way is using the browser developer tools, especially Performance tool which can help you to evaluate overall responsiveness and profile JavaScript code.
Once you fix all the issues and are more or less happy with the client-side performance you can use WebDriver Sampler which provides JMeter integration with Selenium browser automation framework for the regression testing purposes so if adding new features or bug fixes will cause client-side performance degradation you will catch it