REI Integration

Note: REI integration only works on Fabric in 1.16. In 1.18+, it works on both Forge and Fabric!

All REI events are client sided and so go in the client_scripts folder

Hide Items

onEvent('rei.hide.items', event => {

Add Items

onEvent('rei.add.items', event => {
  event.add(item.of('example:item').nbt({test: 123}))

Add Information

onEvent('rei.information', event => {
  event.add('example:ingredient', 'Title', ['Line 1', 'Line 2'])

Yeet categories

onEvent('rei.remove.categories', event => {
  console.log(event.getCategoryIds()) //log a list of all category ids to logs/kubejs/client.txt
  //event.remove works too, but yeeting is so much more fun 😉

Grouping / Collapsible Entries (1.18.2+)

onEvent("", (event) => {
    // This event allows you to add custom entry groups to REI, which can be used to clean up the entry list significantly.
    // As a simple example, we can add a "Swords" group which will contain all (vanilla) swords
    // Note that each group will need an id (ResourceLocation) and a display name (Component / String)
    event.groupItems("kubejs:rei_groups/swords", "Swords", [

    // An easy use case for grouping stuff together could be using tags:
    // In this case, we want all the Hanging Signs and Sign Posts from Supplementaries to be grouped together
    event.groupItemsByTag("supplementaries:rei_groups/hanging_signs", "Hanging Signs", "supplementaries:hanging_signs");
    event.groupItemsByTag("supplementaries:rei_groups/sign_posts", "Sign Posts", "supplementaries:sign_posts");

    // Another example: We want all of these items to be grouped together ignoring NBT,
    // so you don't have a bajillion potions and enchanted books cluttering up REI anymore
    const useNbt = ["potion", "enchanted_book", "splash_potion", "tipped_arrow", "lingering_potion"];

    useNbt.forEach((id) => {
        const item = Item.of(id);
        const { namespace, path } =;
        event.groupSameItem(`kubejs:rei_groups/${namespace}/${path}`, item.getName(), item);

    // Items can also be grouped using anything that can be expressed as an IngredientJS,
    // including for example regular expressions or lists of ingredients
    event.groupItems("kubejs:rei_groups/spawn_eggs", "Spawn Eggs", [

    // you can even use custom predicates for grouping, like so:
    event.groupItemsIf("kubejs:rei_groups/looting_stuff", "Stuff with Looting I", (item) =>
        // this would group together all items that have the Looting I enchantment on them
        item.hasEnchantment("minecraft:looting", 1)

    // you can also group fluids in much the same way as you can group items, for instance:
    event.groupFluidsByTag("kubejs:rei_groups/fluid_tagged_as_water", `"Water" (yeah right lmao)`, "minecraft:water");