1. A development method for a web application system, comprising: in a running state of the web application system, performing the following steps at a server of the web application system: providing a developer interface to a remote client developer device for the web application system; generating or modifying a script code used to perform a predetermined function; parsing, by a script parser, the generated script code or the modified script code to correspondingly generate an object type which performs a new function, or to modify an object type which performs an existing function; generating a new function object or modifying an existing function object, by an object manager, according to the generated object type which performs the new function or the modified object type which performs the existing function; assigning a unique identifier to each generated or modified object type; organizing, by the object manager invoking relationships between the new function object and other objects, or invoking relationships between the modified function object and other objects by setting the invoking relationships using the assigned unique identifiers; and allowing the web application system to perform the predetermined function based on the generated new function object or the modified existing function object while remaining in the running state.