Super Mario Construct is an upcoming HTML5 Mario editor made by Luigibonus (sprites by Nintendo, AmazingAlien and Tristaph ). It is intended to be a successor of Super Mario Flash 2 and all other SMF games, as Adobe Flash will be discontinued in 2020. The name Super Mario Construct was chosen because of the ability to create (construct) Mario levels, to immediately show that the game includes a Level Editor, and that the game is being developed in what is currently the most powerful HTML5 game engine, Construct.
The game is still in development, but there is a playable demo that can be played at this link (pre-release2).
It includes a various amount of Mario moves, including the all-new Spinjump.
There is also a fully functional level editor which already supports generating and loading level codes, so levels being made in the current demo can indeed be saved and shared with other people.
For the guide, FaQ and Changelogs maintained by The Flying Dutchman, click this link , it holds a ton of information which could clear up several of your questions about Super Mario Construct.