x1 - undefined (вроде бы не должен быть) [закрыт]

function d(x1, y1, x2, y2, x3, y3, x4, y4) { 
  let x, y; 
  x = ((x1 * y2 - x2 * y1) * (x4 - x3) - (x3 * y4 - x4 * y3) * (x2 - x1)) / ((y1 - y2) * (x4 - x3) - (y3 - y4) * (x2 - x1)); 
  y = ((y3 - y4) * x - (x3 * y4 - x4 * y3)) / (x4 - x3); 
  return x, y; 
} 
console.log(d(0, 0, 120, 90, 0, 60, 120, 60));

function d(x1, y1) { 
  let x, y; 
  x = x1 * y1 
  y = x1 + y1 
  return x, y; 
} 
console.log(d(120, 60));