Only typeset displayed data if needed

[jasongrout]

In

notebook/notebook/static/notebook/js/outputarea.js

Line 651 in 39a706c

OutputArea.prototype.append_display_data = function (json, handle_inserted) {

, the entire output area is typeset if any display_data message has an html, markdown or latex mimetype. This is problematic:

1. Just because the mimetype exists doesn't mean it was the one that was rendered. We should be checking to see if the latex, html, or markdown mimetype was actually the one displayed.
2. We shouldn't typeset the entire output area, just the display data that we just added.

This came up in jupyter-widgets/ipywidgets#1777. #2444 may also be related.

[jasongrout]

This logic also happens in

notebook/notebook/static/notebook/js/outputarea.js

Line 498 in 39a706c

this.typeset();

and

notebook/notebook/static/notebook/js/outputarea.js

Line 632 in 39a706c

this.typeset();

[rgbkrk]

Oh gosh, yes thank you for bringing this up. We at times have been displaying large tables and they take forever to render because MathJax is typesetting them.

[takluyver]

This is at risk of being bumped unless someone finds time to work on it.

[rgbkrk]

I'm currently designing with typesetting only happening on markdown areas and latex output.