Function getOldSpans

static/editor.md/lib/codemirror/lib/codemirror.js:7793–7799

(doc, change)

  // Retrieve and filter the old marked spans stored in a change event.
  function getOldSpans(doc, change) {
    var found = change["spans_" + doc.id];
    if (!found) return null;
    for (var i = 0, nw = []; i < change.text.length; ++i)
      nw.push(removeClearedSpans(found[i]));
    return nw;
  }

  // Used both to provide a JSON-safe object in .getHistory, and, when
  // detaching a document, to split the history in two