Backpack:
Lua Code:
local itemData = PLAYER_INVENTORY:GetBackpackItem(slotIndex)
Bank:
Lua Code:
local itemData = PLAYER_INVENTORY:GetBankItem(slotIndex)
Or directly from the table:
Lua Code:
local itemData = PLAYER_INVENTORY.inventories[inventoryType].slots[slotIndex]
inventoryType:
INVENTORY_BACKPACK = 1
INVENTORY_QUEST_ITEM = 2
INVENTORY_BANK = 3
INVENTORY_GUILD_BANK = 4