Aseprite script to export visible layers as PNG files

Export Layers.lua

function GetVisibleLayers()
    data = {}
    for _, layer in ipairs(app.activeSprite.layers) do
        if layer.isVisible then
            table.insert(data, layer)
        end
    end
    return data
end

function RestoreVisibleLayers(data)
    for _, layer in ipairs(data) do
        layer.isVisible = true
    end
end

function GetFileName(str)
    return str:match(".+[/\\](.+)%.")
end

function GetDirName(str)
    return str:match("(.*[/\\])")
end

local sprite = app.activeSprite
visible_layers = GetVisibleLayers()

for _, layer in ipairs(sprite.layers) do
    layer.isVisible = false
end

for i, layer in ipairs(visible_layers) do
    layer.isVisible = true
    local dir = GetDirName(sprite.filename)
    local spriteName = GetFileName(sprite.filename)
    local layerFileName = dir .. spriteName .. "-" .. i .. ".png"
    app.activeSprite:saveCopyAs(layerFileName)
    layer.isVisible = false
end

RestoreVisibleLayers(visible_layers)