ESX Framework Development

Complete guide for developing with ESX Legacy Framework — the most trusted FiveM roleplay framework since 2017.

When to use

• Creating or editing ESX resources/scripts
• Working with player data (xPlayer, PlayerData)
• Implementing jobs, economy, inventory, or weapon systems
• Using ESX client/server functions, callbacks, or events
• Questions about ESX best practices and optimization

How to use

Read individual rule files for detailed explanations and examples:

• rules/core-concepts.md — ESX architecture, PlayerData, xPlayer object, framework initialization

• rules/client-functions.md — Client-side ESX functions, UI systems, player state management

• rules/server-functions.md — Server-side functions, player retrieval, callbacks, triggers

• rules/xplayer-methods.md — xPlayer object methods: money, items, weapons, inventory, jobs, metadata

• rules/jobs-economy.md — Job system, salaries, accounts (money/bank), society management

• rules/inventory-items.md — Inventory system, item management, usable items, weight calculations

• rules/weapons-loadout.md — Weapon system, loadout, components, ammo, tints

• rules/events-callbacks.md — ESX events, server callbacks, client callbacks, secure net events

• rules/best-practices.md — ESX coding standards, optimization, security, naming conventions

• rules/reference-links.md — Official ESX documentation links

Key principles

1. Always check for nil — if xPlayer then ... end before using xPlayer
2. Use ESX.GetPlayerFromId — Standard player retrieval: local xPlayer = ESX.GetPlayerFromId(source)
3. Wait for player load — Check ESX.IsPlayerLoaded() on client before accessing PlayerData
4. Never trust client — Validate all data server-side, use SecureNetEvent for client events
5. Follow ESX patterns — Use ESX functions instead of reinventing (callbacks, notifications, etc.)
6. Optimize loops — Cache player objects, avoid unnecessary GetPlayerFromId calls
7. Use camelCase — Follow Lua naming: myVariable, MyGlobalFunction, MY_CONSTANT
8. Minimal globals — Keep variables local unless they need global scope
9. Use ox_lib for UI — Prefer ox_lib for menus, dialogs, notifications, progress bars instead of ESX UI