A Weighted Item Stack is like a normal IItemStack but has a percentage added to it.
You normally use them when dealing with percentage based actions like drops or secondary outputs.

It might be required for you to import the package if you encounter any issues (like casting an Array), so better be safe than sorry and add the import.
import crafttweaker.item.WeightedItemStack;

WeightedItemStack implements IWeightedIngredient. That means all functions available to IWeightedIngredient also are available to WeightedItemStack.

You can derive a weightedItemStack from an IItemStack by either using the modulo operator or the weight function on it.

ZenScript
 Copy
val itemStack = <minecraft:dirt>;

//both create a weightedItemstack object with a chance of 20%
val wItemStack = itemStack % 20;
val wItemStack2 = itemStack.weight(0.2);

ZenGetter	What does it do	戻り値
ZenGetter stack	What does it do Returns the associated itemStack	戻り値 IItemStack
ZenGetter chance	What does it do Returns the stack's chance as decimal (e.g. 0.2)	戻り値 float
ZenGetter percent	What does it do Returns the stack's chance as percentage (e.g. 20.0)	戻り値 float