title: Find the opposite of a direction angle (360 degrees) in JavaScript
body: <p>The following question: <a href="https://math.stackexchange.com/questions/1319615/how-to-calculate-opposite-direction-angle">https://math.stackexchange.com/questions/1319615/how-to-calculate-opposite-direction-angle</a> shows the formula for doing this. How would I write this: <code>(α+180) mod 360</code> in javascript. (a is a variable)</p>