getSvgArcPath.js

function polarToCartesian(centerX, centerY, radius, angleInDegrees) {
    var angleInRadians = (angleInDegrees-90) * Math.PI / 180.0;
  
    return {
    x: centerX + (radius * Math.cos(angleInRadians)),
    y: centerY + (radius * Math.sin(angleInRadians))
    };
}
  
function getArcPath(centerX, centerY, radius, startAngle, endAngle){
    var start = polarToCartesian(centerX, centerY, radius, endAngle);
    var end = polarToCartesian(centerX, centerY, radius, startAngle);

    var largeArcFlag = endAngle - startAngle <= 180 ? "0" : "1";

    var d = [
        "M", start.x, start.y, 
        "A", radius, radius, 0, largeArcFlag, 0, end.x, end.y
    ].join(" ");

    return d;       
}