Q:

Display cell value in tooltip after hovering over a cell in DT::datatable

How do I utilize javascript to display the cell value in a tooltip after hovering over a particular cell in a DT::datatable? I decided to hide the long text after a certain width is reached (overflow-x: hidden; white-space: nowrap;) to maintain a clean format, and I would like the user to be able to see the full text if they choose to hover over a given cell.
datatable(df,
          class="compact",
          selection="none",
          rownames=F,
          colnames=NULL,
          options=list(dom="t",
                       pageLength=10
          ),
          escape=F)

A:

Could you try this:
datatable(head(iris), 
          options=list(initComplete = JS("function(settings) {var table=settings.oInstance.api(); table.$('td').each(function(){this.setAttribute('title', $(this).html())})}")))

This sets a tooltip for every cell.
To set the tooltip for a single specific cell:
datatable(head(iris), 
          options=list(initComplete = JS(
            "function(settings) {
            var table = settings.oInstance.api();
            var cell = table.cell(2,2);
            cell.node().setAttribute('title', cell.data());
            }")))

