Patterns for talking between NUI and Lua

Every NUI resource has the same plumbing: Lua sends data to the page, the page asks Lua to do things, and anything that matters goes on to the server. Getting that plumbing right — one message convention, one callback helper, validation on the server — keeps complex UIs like phones and inventories maintainable.

RegisterNuiCallback('bank:transfer', function(data, cb)
    if type(data.to) ~= 'number' or type(data.amount) ~= 'number' then
        return cb({ ok = false, error = 'invalid' })
    end
    local result = lib.callback.await('bank:transfer', false, data.to, data.amount)
    cb(result)
end)

lib.callback.register('bank:transfer', function(source, to, amount)
    -- validate target, amount limits, balance; then move money
    return { ok = true }
end)

The page sees one fetch that resolves with the server’s answer. Details: NUI callbacks and callbacks explained.

• SetNuiFocus(true, true) on open; SetNuiFocus(false, false) on every close path and on resource stop.
• A close callback from the page (Escape key) so Lua can release focus.
• Details: NUI focus and cursor.

Type message payloads once and share them between Lua docs and the frontend; keep the Lua layer thin (validation and forwarding) and put business rules on the server. A React structure that follows these patterns: React NUI boilerplate.

Players can call NUI callbacks from the devtools with any data. Treat callback input like any client input: validate types in Lua and re-check everything on the server — see secure server events.