QGIS/resources/function_help/json/is_selected

{
  "name": "is_selected",
  "type": "function",
  "description": "Returns if a feature is selected. If called with no parameters checks the current feature.",
  "arguments": [
        {
          "arg":"feature",
          "optional": true,
          "default": "current feature",
          "description":"The feature which should be checked for selection."
        },
        {
          "arg": "layer",
          "optional": true,
          "default": "current layer",
          "description": "The layer (or its id or name) on which the selection will be checked."
        }
  ],
  "examples": [
	{ "expression":"is_selected()", "returns" : "True if the current feature is selected."},
	{ "expression":"is_selected(get_feature('streets', 'name', \"street_name\"), 'streets')", "returns":"True if the current building's street is selected."}
  ]
}