Represent minecraft windows. Check mineflayer-web-inventory to display windows.
Read the API.
const windows = require('prismarine-windows')('1.8')
const Item = require('prismarine-item')('1.8')
const inv = windows.createWindow(1, 'minecraft:inventory', 'inv', 36)
inv.updateSlot(10, new Item(256, 1))
console.log(inv.items())