applies highlighting with a inline element recursively

highlight_nodes_recursively

function highlightNodes(el, tagName) {
	for ( let element of el.childNodes ) {
  	if ( element.childNodes.length === 0 && element.nodeType === Node.TEXT_NODE) {
			const newChild = document.createElement(tagName)
      newChild.innerText = element.nodeValue
      element.parentElement.replaceChild(newChild, element)
    }
    else {
    	highlightNodes(element, tagName)
    }
  }
}
// No spaces should be present in the source html
const el = document.getElementById("foo")
highlightNodes(el, "i")