Changing the stroke-linecap of a polyline in leaflet

gistfile1.js

testPolyline = new L.Polyline(
[[34.03900467904445,-118.55810165405272],
[34.13766755862196,-118.50643157958984],
[34.15187463170986,-118.36292266845702],
[34.168635904722734,-118.3292770385742],
[34.16196020316907,-118.25923919677734]]);

testPolyline.addTo(map);

//Left-click makes it flat
testPolyline.on('click',function() {
  this._path.style["stroke-linecap"] = "butt";
});

//Right-click makes it round
testPolyline.on('contextmenu',function() {
  this._path.style["stroke-linecap"] = "round";
});