- [Instructor] When we're developing a web application, it's not guaranteed that the data services we need will be available during development. This is especially troublesome, if our application is data-driven and makes many requests to a data service. Wouldn't it be handy if we could mock a RESTful service? Well, we can. There's an NPM package called JSON Server. That's particularly useful, if the data end point returns, JSON. It claims to provide a full fake REST API with zero-coding in less than 30 seconds. And it pretty much does. To use it, you need a JSON file that will act as your database and an NPM installation of JSON Server. You can see the command for a global installation here on the screen. Once installed, point JSON server at your file with the minus minus watch switch, and hey, presto, Just to know for using with React, JSON server runs on port 3000 by default, which is the same port as our React server. You can change the port in JSON Server by adding the -p switch and an alternative number, say 4,000. Here we have a JSON file that contains some JSON data about courses. You can see that it is a properly formed JSON file. It has an initial key of courses. And this is an array of course objects. Firing up JSON server to watch this file and navigating to local hosts 4,000/courses yields all of the courses in the file. If I use the RESTful for path courses/1, you can see that we get the course with the id of one return. The console shows details of the requests that we have made We've made get requests, but we could also use any valid HTTP request type to JSON server, such as post, put, update and delete. This tool is really useful for us as it lets us build the correct functionality into our application, without needing the actual end service. We can make requests and ensure that they work. We simply change the request URL to the one for the actual service before deployment.