javascript atan2() 计算X 轴到某一点的角度

<code class="language-javascript">Math.atan2(y, x)</code>

<code class="language-javascript"><script type="text/javascript">
document.write(Math.atan2(0.50,0.50) + "<br />")
document.write(Math.atan2(-0.50,-0.50) + "<br />")
document.write(Math.atan2(5,5) + "<br />")
document.write(Math.atan2(10,20) + "<br />")
document.write(Math.atan2(-5,-5) + "<br />")
document.write(Math.atan2(-10,10) + "<br />")
document.write(Math.atan2("s","y") + "<br />")
</script></code>

<code class="language-javascript">0.7853981633974483
-2.356194490192345
0.7853981633974483
0.4636476090008061
-2.356194490192345
-0.7853981633974483
NaN</code>