MerchantJS

MerchantJS is a Forge addon for KubeJS that extends the trading system. Scripts use it to initiate trades anywhere in the world, so an entity that cannot normally trade can offer custom trades through a customizable trading screen. Setting maxUses to 0 makes a trade appear unavailable, which lets scripts enable and disable offers selectively, a common way to gate trades behind stage-based progression.

The mod focuses on creating additional trades quickly rather than replacing vanilla trading, which already includes many mechanics. Event hooks can combine MerchantJS with dynamic trade control, and an event fires after a trade occurs, including for vanilla trades, so scripts can trigger further actions once a player has traded. Restocking is checked at an interval whenever a trade window is opened.

Features such as restocking by experience, demand, or price fluctuation are not built in, so a script author must implement them. Stock information and other trade-related data must be stored by the script, and KubeJS persistentData is suited to that purpose. Offers are defined anew each time openMerchant is called, and a refresh of trade data is needed only when the script calls for one. Servers that run it need every player to install it too. Files are published for Forge, with 1.0.0 for 1.20.6 as the latest file, and the code is open source under the GNU General Public License v3.0 only.