how to get angle in javascript between two points

Question

in the above image ineed the angle between the two points

if green dot is considered as origin (px,py) ie (0,0) and red dot is (ax,ay)

by the way in the above image angle should be around 45 degree.... acute angle

more ex:

3:00 is 0 degree 12:00 is 90 degree 9:00 is 180 degree 6:00 is 270 degree

here's the code i have tried so far:

function angle(cx, cy, ex, ey) {
var dy = ey - cy;
var dx = ex - cx;
var theta = Math.atan2(dy, dx); // range (-PI, PI]
theta *= 180 / Math.PI; // rads to degs, range (-180, 180]
if (theta < 0) theta = 360 + theta; // range [0, 360)
return theta;
}

Answer 1

Try this out, Working fine for me.

function angle(cx, cy, ex, ey) {
  var dy = ey - cy;
  var dx = ex - cx;
  var theta = Math.atan2(dy, dx); // range (-PI, PI]
  theta *= 180 / Math.PI; // rads to degs, range (-180, 180]
  //if (theta < 0) theta = 360 + theta; // range [0, 360)
  return theta;
}