Modify your first loot table

Let's get started with modifying your first loot table. LootJS offers different functions you can use for that. You will be able to add, remove or even just change the weight of an item in the loot table. Before starting make sure to have a basic knowledge on how loot tables work, check out the minecraft wiki for that.

First create a javascript file in server_scripts and you can call the file however you want but make sure the file extension will be .js, e.g more_loot.js.

We will use the minecraft:chests/desert_pyramide loot table as an example. You can see here how the loot table is structured to get a better understanding of what we will.

Add Item

Let's add a simple apple to our chest loot.

LootJS.lootTables(event => {
    event.getLootTable("minecraft:chests/desert_pyramid").firstPool().addEntry("minecraft:apple")
})

Note that we use firstPool() here. We will use this a lot to always get the first loot pool. Most vanilla tables do have one pool which will roll multiple times, see rolls.

With weight

But what if we want to add the apple with a specific weight? For this we can simply use LootEntry, which has the functionality to set the weight.

LootJS.lootTables(event => {
    event
        .getLootTable("minecraft:chests/desert_pyramid")
        .firstPool()
        .addEntry(LootEntry.of("minecraft:apple").withWeight(20))
})

Set quantity

Let's also change the quantity of the apple, so it will drop 2 - 5 apples each time an apple is rolled. We can use the setCount function.

LootJS.lootTables(event => {
    event
        .getLootTable("minecraft:chests/desert_pyramid")
        .firstPool()
        .addEntry(LootEntry.of("minecraft:apple").withWeight(20).setCount([2, 5]))
})

Modify Item

Now we want to modify an existing entry inside our loot table. You can see that diamonds have a weight of 5, let's change it to 1 to make it less likely to be rolled.

LootJS.lootTables(event => {
    event
        .getLootTable("minecraft:chests/desert_pyramid")
        .firstPool()
        .modifyItem(itemEntry => {
            if (itemEntry.item.id === "minecraft:diamond") {
                itemEntry.setWeight(1)
            }

            return itemEntry
        })
})

You can see that we return itemEntry again. This is required because modify operations always require a result. In our example we just modify the given itemEntry and return it, this will ensure that all conditions and loot modifiers will still be applied for the entry. Alternative you can just return a new LootEntry with the desired modifications.

Remove Item

We also want to remove minecraft:bone from our desert pyramids loot table. removeItem takes an ItemFilter as an argument, in our case we just want to remove bones, so we can simply use the item id as argument.

LootJS.lootTables(event => {
    event.getLootTable("minecraft:chests/desert_pyramid").firstPool().removeItem("minecraft:bone")
})