findtinyelements.js

function getFontSize(n) {
  return parseInt(window.getComputedStyle(n, null).getPropertyValue('font-size'))
}

function renderNode(n) {
  let output = [n.tagName]
  n.id && output.push(`id="${n.id}"`)
  n.className && output.push(`class="${n.className}"`)
  return output.join(' ')
}

function nodePath(n) {
  let parents = [n]

  let parent = n.parentElement
  while(parent) {
    parents.push(parent)
    parent = parent.parentElement
    break
  }

  return parents.reverse().map(renderNode).join(' > ')

}

function checkNode(n) {
  if(n.nodeType === Node.TEXT_NODE) {
    return
  }

  if(getFontSize(n) < 12) {
    console.log(nodePath(n))
  }

  n.childNodes.forEach(checkNode)
}

checkNode(document.querySelector('body'))