How can I style last row using jsPDF Autotable plugin?

To change styles dynamically you have two options. The first is to use didParseCell to change autoTable styles:

doc.autoTable({
    html: '#table',
    didParseCell: function (data) {
        var rows = data.table.body;
        if (data.row.index === rows.length - 1) {
            data.cell.styles.fillColor = [239, 154, 154];
        }
    }
});

The second is to use willDrawCell if you'd rather use jspdf styling functions:

doc.autoTable({
    html: '#table',
    willDrawCell: function (data) {
        var rows = data.table.body;
        if (data.row.index === rows.length - 1) {
            doc.setFillColor(239, 154, 154);
        }
    },
});

See more advanced examples here.

It has been almost three years since the last response to this question. I was struggling a bit to achieve that effect with drawCell function. In jspdf-autotable": "^3.0.10" you should use one of three following callbacks to achieve what you want:

    // Use to change the content of the cell before width calculations etc are performed
    didParseCell: function (data) {
    },
    willDrawCell: function (data) { 
    },
    // Use to draw additional content such as images in table cells
    didDrawCell: function (data) {
    },

In your case willDrawCell is the one you want to use. So the code will be something like:

doc.autoTable({
  columns,
  body,
  headStyles: {
    fillColor: "#0d47a1"
  },
  willDrawCell: drawCell
});

let drawCell = function(data) {
  var doc = data.doc;
  var rows = data.table.body;
  if (rows.length === 1) {
  } else if (data.row.index === rows.length - 1) {
    doc.setFontStyle("bold");
    doc.setFontSize("10");
    doc.setFillColor(255, 255, 255);
  }
};