JavaScript: Calculate polar angle in degree (φ) from a cursor position and a midpoint center

getPolarAngle.ts

 // Read this article for full understanding: https://de.serlo.org/mathe/45643/polarkoordinaten
  
// We need two coordinates for this calculation: the cursor coordinate and midpoint coordinate.

// How the sricpt works:
// 1. It calculates the distance between the points
// 2. It calculates the polar angle (in degree)
// 3. If the coordinates are overlapping, it calculates the edge cases also.
// It returns the polar angle as a number
  
const getPolarAngle = (cursor: {x: number; y: number}, midpoint: {x: number; y: number}): number => {
  /* Degree */
  let polarX: number;
  let polarY: number;
  let polarDegree: number = 0;
  // First case
  if(midpoint && cursor) {
    if (midpoint.x < cursor.x && midpoint.y < cursor.y) {
      polarX = cursor.x - midpoint.x;
      polarY = cursor.y - midpoint.y;
      console.log('first', polarX, polarY);
      polarDegree = ~~(Math.atan(polarY/polarX) * (180/Math.PI) + 180)
    }
    // Second Case
    if (midpoint.x > cursor.x && midpoint.y < cursor.y) {   
      polarX = midpoint.x - cursor.x;
      polarY = midpoint.y - cursor.y;
      console.log('second', polarX, polarY);
      polarDegree = ~~(Math.atan(polarY/polarX) * (180/Math.PI))
    }
    // Third Case
    if(midpoint.x < cursor.x && midpoint.y > cursor.y) {
      polarX = cursor.x - midpoint.x;
      polarY = cursor.y - midpoint.y;
      console.log('third', polarX, polarY);
      polarDegree = ~~(Math.atan(polarY/polarX) * (180/Math.PI) + 180)
    }
    // Forth case
    if(midpoint.x > cursor.x && midpoint.y > cursor.y) {
      polarX = midpoint.x - cursor.x;
      polarY = midpoint.y - cursor.y;
      console.log('forth', polarX, polarY);
      polarDegree = ~~(Math.atan(polarY/polarX) * (180/Math.PI))
    }
    /* Overlapping values */
    if (midpoint.x === cursor.x && midpoint.y > cursor.y) {
      return -270 // Bottom
    } else if (midpoint.x === cursor.x && midpoint.y < cursor.y) {
      return -90; // Top
    } else if (midpoint.x === cursor.x && midpoint.y === cursor.y) {
      return 180; // Middle
    } else if (midpoint.y === cursor.y && midpoint.x < cursor.x) {
      return -180; // Left
    } else if (midpoint.y === cursor.y && midpoint.x > cursor.x) {
      return 0; // Right
    }
  }

  return polarDegree;
}