Apply auto-layout for multiple frames on Figma

index.js

const layoutMode = 'HORIZONTAL' // 'HORIZONTAL' or 'VERTICAL'
figma.currentPage.selection.forEach(node => {
  if (node.type === 'FRAME') {
    const firstItemPosition = layoutMode === 'HORIZONTAL' ? node.children[0].x : node.children[0].y
    const firstItemSize = layoutMode === 'HORIZONTAL' ? node.children[0].width : node.children[0].height
    const secondItemPosition = layoutMode === 'HORIZONTAL' ? node.children[1].x : node.children[1].y
    const itemSpacing = secondItemPosition - (firstItemPosition + firstItemSize)

    node.layoutMode = layoutMode
    node.itemSpacing = itemSpacing
    if (layoutMode === 'HORIZONTAL') {
      node.paddingLeft = firstItemPosition
      node.paddingRight = firstItemPosition
    } else {
      node.paddingTop = firstItemPosition
      node.paddingTop = firstItemPosition
    }
  }
})