code.ts

const command = figma.command;

function getContaining(item:SceneNode, targetType:string):SceneNode|null {
  if(item.parent) {
    if(item.parent.type === targetType) {
      return item.parent as SceneNode;
    }
    else {
      return getContaining(item.parent as SceneNode, targetType);
    }
  }
  else return null;
}

function getTop(item:SceneNode, targetType:string):SceneNode|null {
  console.log("Get Top",item, targetType);
  let outerNode:SceneNode|null = null;
  if(item.type === targetType) {
    outerNode = item;
  }
  let checkItem = item;
  while(checkItem.parent) {
    if(checkItem.parent.type === targetType) {
      outerNode = checkItem.parent as SceneNode;
    }
    checkItem = checkItem.parent as SceneNode;
  }
  return outerNode;
}

let commandArgs = {
  "containingInstance": {callback:getContaining, type:"INSTANCE"},
  "topInstance": {callback:getTop, type:"INSTANCE"},
  "containingFrame": {callback:getContaining, type:"FRAME"},
  "topFrame": {callback:getTop, type:"FRAME"},
  "containingGroup": {callback:getContaining, type:"GROUP"},
  "topGroup": {callback:getTop, type:"GROUP"}
}[command];

let selection = figma.currentPage.selection.map(selectedItem=>commandArgs.callback(selectedItem, commandArgs.type)).filter(val=>val!==null);

if(selection.length>0) figma.currentPage.selection = selection;
else {
  console.log(`No ${commandArgs.type.toLowerCase()}s above selection`);
  figma.notify(`Selection is not the child of any ${commandArgs.type.toLowerCase()}s.`);
}
// Make sure to close the plugin when you're done. Otherwise the plugin will
// keep running, which shows the cancel button at the bottom of the screen.
figma.closePlugin();