mongodb do database nodejs write server-side html + css + js write browser-side what knowledge is needed it is difficult to say exactly, the business is a must know, the basic technology such as the api of each environment, the js language, the page design and refactoring is also a must, and then up to the architectural design of the entire system, the design of the underlying data structure, the design of the algorithms, in fact, is not the need for which knowledge, but, you will be able to use, if you will, I think big data, machine learning can be used.