extractHTMLFromTextMorph (via dom range)

foo.js

export function extractHTMLFromTextMorph(textMorph, range) {

    // let html = extractHTMLFromTextMorph(this, this.selection);
    evt.domEvt.clipboardData.setData("text/html", textLayerNode.outerHTML);

  let node = textMorph.env.renderer.getNodeForMorph(textMorph),
      textLength = this.document.stringSize,
      firstLineNode = node.querySelector(".newtext-text-layer.actual"),
      // _ = console.log(`START, looking for ${textMorph.positionToIndex(range.start)}`),
      start = findNodeWithOffsetAt(textMorph.positionToIndex(range.start), firstLineNode, undefined, textLength, false),
      // _3 = console.log(`END, looking for ${textMorph.positionToIndex(range.end)}`),
      end = findNodeWithOffsetAt(textMorph.positionToIndex(range.end), firstLineNode, undefined, textLength, false),
      el = document.createElement("div"),
      r = document.createRange()

  r.setStart(start.node, start.offset);
  r.setEnd(end.node, end.offset);
  el.appendChild(r.cloneContents()/*fragment*/);
  return el.innerHTML;
}

function findNodeWithOffsetAt(index, node, currentIndex = 0, maxLength = Infinity, debug = false) {
  if (index >= maxLength) return {offset: 0, node, found: true};
  if (index == currentIndex) return {offset: 0, node, found: true};

  let {TEXT_NODE, ELEMENT_NODE} = node;

  if (node.nodeType === TEXT_NODE) {
    debug && console.log(`In text node ${currentIndex} "${node.textContent}"`);
    var nextIndex = currentIndex + node.length;
    if (index < nextIndex) {
      debug && console.log({node, found: true, offset: index - currentIndex}, currentIndex);
      return {node, found: true, offset: index - currentIndex};

    } else if (index === nextIndex) {
      // at line end = newline
      debug && console.log({node, found: true, offset: node.length});
      return {node, found: true, offset: node.length};
    }
    currentIndex = nextIndex;

  } else if (node.nodeType === ELEMENT_NODE) {

    if (String(node.tagName).toLowerCase() === "br") {
      currentIndex = currentIndex + 1;
      if (index === currentIndex) {
        debug && console.log({node, found: true, offset: 0})
        return {node, found: true, offset: 0};
      }

    } else {
      debug && console.log(`In element node  ${currentIndex} "${node}"`);
      for (let child of node.childNodes) {
        let result = findNodeWithOffsetAt(index, child, currentIndex, maxLength, debug);
        if (result.found) return result;
        currentIndex = result.currentIndex;
      }
    }

  }

  return {offset: 0, node, found: false, currentIndex};
}