Chapter 21
JavaScript Reference

Math.atan2() Function

Name

Math.atan2() Function---compute the angle from the X axis to a point

Synopsis

Math.atan2(x, y)

Arguments

x

The X-coordinate of the point.

y

The Y-coordinate of the point.

Returns

The counter-clockwise angle, measured in radians, between the positive X axis, and the point (x, y).

Description

The Math.atan2() function performs half of the conversion between Cartesian coordinates and polar coordinates. It computes and returns the angle theta of an (x, y) point.

This function is named Math.atan2() because it performs a similar computation to Math.atan(). Math.atan2() is passed separate x and y arguments, and Math.atan() is passed the ratio of those two arguments.