The data is obtained from any source: file, database, content, or other form. Then you will have to make sure to define where you will get that information and in agreement you will need to do one thing or another. For example, if it is from a database, the structure creates it with a server language. if it is for a series of content that the user enters, he would have to provide several form controls and the possibility of adding several records. then with javascript you iterate the records and you are adding the information to the json creating the necessary properties.