此方法返回弧度的反正切。atan方法返回一个在-pi/2和π/2弧度之间的数值。
语法
Math.atan( x ) ;
下面是参数的详细信息:
返回值:
例子:
<html> <head> <title>JavaScript Math atan() Method</title> </head> <body> <script type="text/javascript"> var value = Math.atan(-1); document.write("First Test Value : " + value ); var value = Math.atan(.5); document.write("<br />Second Test Value : " + value ); var value = Math.atan(30); document.write("<br />Third Test Value : " + value ); var value = Math.atan("string"); document.write("<br />Fourth Test Value : " + value ); </script> </body> </html>
这将产生以下结果:
First Test Value : -0.7853981633974483 Second Test Value : 0.4636476090008061 Third Test Value : 1.5374753309166493 Fourth Test Value : NaN