json-add-to-object

json-add-to-object is a compiled Lisp function in `json.el'.

(json-add-to-object OBJECT KEY VALUE)

Add a new KEY -> VALUE association to OBJECT.
Returns the updated object, which you should save, e.g.:
(setq obj (json-add-to-object obj "foo" "bar"))
Please see the documentation of `json-object-type' and `json-key-type'.