It may make senses to add a "live preview" feature for some datatypes that currently does not have (see T325429: Live preview for certain data types), but it make no senses for string and monolingual string datatype.

However, one wbparsevalue and one wbformatvalue is called for each modification of string property value, which result is used nowhere in the UI. For monolingual and external ID datatype statement one wbparsevalue and two wbformatvalue is called.

Proposed solutions:

• Eliminate all wbparsevalue and wbformatvalue calls when editing some datatype statement (at least string, external-id and monolingual text)
• If the result of wbformatvalue is used somewhere we can still optimize the process by either:
  • Move the parse and format process to client side and eliminate all API calls to wbparsevalue and wbformatvalue
  • Or make a new API to combine these two or three API calls (which will save one or two web request for each modification)