The code draws only the wedge ... circle drawn here for perspective only.
// Usage
var wedge={
cx:150, cy:150,
radius:100,
startAngle:0,
endAngle:Math.PI*.65
}
drawWedge(wedge,'skyblue','gray',4);
function drawWedge(w,fill,stroke,strokewidth){
ctx.beginPath();
ctx.moveTo(w.cx, w.cy);
ctx.arc(w.cx, w.cy, w.radius, w.startAngle, w.endAngle);
ctx.closePath();
ctx.fillStyle=fill;
ctx.fill();
ctx.strokeStyle=stroke;
ctx.lineWidth=strokewidth;
ctx.stroke();
}