function loadTemplateAsync(path) {
  const result = new Promise(resolve => {
    const xhttp = new XMLHttpRequest()

    xhttp.onreadystatechange = function () {
      if (this.readyState == 4) {
        if (this.status == 200) resolve(this.responseText)

        if (this.status == 404) resolve(`<div>Page not found: ${path}</div>`)
      }
    }

    xhttp.open('GET', path, true)
    xhttp.send()
  })

  return result
}

function imgSizeFit(img, maxWidth = 1024, maxHeight = 768) {
  let ratio = Math.min(
    1,
    maxWidth / img.naturalWidth,
    maxHeight / img.naturalHeight
  )
  return {width: img.naturalWidth * ratio, height: img.naturalHeight * ratio}
}