Right now we use codemirror's JavaScript mode on the website but there's a JSX mode now so we should start using that instead.

for (var i = 0; i < len; ++i) {
        if (isNeutral.test(types[i])) {
          for (var end = i + 1; end < len && isNeutral.test(types[end]); ++end) {}
          var before = (i ? types[i-1] : outerType) == "L";
          var after = (end < len ? types[end] : outerType) == "L";
          var replace = before || after ? "L" : "R";
          for (var j = i; j < end; ++j) types[j] = replace;
          i = end - 1;
        }
      }
      
      
      
      
      
      var order = [], m;
      for (var i = 0; i < len;) {
        if (countsAsLeft.test(types[i])) {
          var start = i;
          for (++i; i < len && countsAsLeft.test(types[i]); ++i) {}
          order.push({from: start, to: i, level: 0});
        } else {
          var pos = i, at = order.length;
          for (++i; i < len && types[i] != "L"; ++i) {}