Filters

Filters are one of the two types of Hooks.

They allow functions to modify data at specific points during script execution. Unlike Actions, filters are designed to operate in isolation and should not cause side effects such as modifying global variables or producing output. Filters are expected to return a modified version of the received data.

Adding a Filter

Adding a filter involves two key steps:

1. Creating a callback function that will process and modify the data.
2. Registering the callback function to a hook, ensuring it gets called at the right moment.

The execution order of filter functions is determined by:

• The manually assigned priority.
• The order in which they were registered, in cases where multiple functions share the same priority.

For example:

• A filter with priority 11 runs after one with priority 10.
• A filter with priority 9 runs before one with priority 10.

To register a filter, use the registerFilter() function with the following parameters:

1. string $hook_name – The name of the filter hook.
2. callable $callback – The function responsible for modifying the data.
3. (Optional) int $priority – The execution priority (default: 10).

The example below will run when the canStartYachtHeist filter is executed in st_yachtheist script with a priority = 10.

function canStart()
    if LocalPlayer.state.isPolice then
        return false
    end
    return false
end
exports.st_yachtheist:registerFilter('canStartYachtHeist', canStart, 10)

This code will do, if the player has state bag isPolice they won't be able to start the yacht heist.

You can refer to the script docs for a list of available hooks.

As you gain more experience, looking through Open Source code will allow you to find the most appropriate hook.