safe-html-template-literal.js

/** @version 0.1 */
const html = (strings, ...values) => (
  Array.from(strings).map((string, index) => (
    string + (
      Array.isArray(values[index])
      ? values[index].join("")
      : (new Option(values[index])).innerHTML
    )
  )).join('')
)

test.html

<script src="safe-html-template-literal.js"></script>
<script>
  document.addEventListener("DOMContentLoaded", () => {
    document.body.innerHTML = html`
      <pre>${"<b>escaped html</b>"}</pre>
      <pre>${["<b>unescaped html</b>"]}<pre>
    `    
  })
</script>