range-selection.js

function newRange(startElement, startOffset, endElement, endOffset) {
  var range = document.createRange();
  range.setStart(startElement, startOffset);
  range.setStart(endElement, endOffset);
  return range;
}

function selectRange(range) {
  window.getSelection().addRange(range);
}

function getCurrentRange() {
  var sel = window.getSelection();
  return (sel.rangeCount > 0) ? sel.getRangeAt(0) : null;
}