Js fixes

@etpinard 

new PR, reverted to before I ran run.py
@chriddyp, @etpinard, this is a slight inconsistency. We require the variable name `plotly_url` for all the exception scripts, but it's specified as `plot_url` everywhere else. Should this be unified? Functionally, it certainly doesn't matter. But it might make the `/matplotlib/` and `/ggplot2/` pages look more like their language counterparts.