Math.atan2()
The Math.atan2()
function returns the arctangent of the quotient of its arguments.
Syntax
Math.atan2(<var>y</var>, <var>x</var>)
Parameters
y
- First number.
x
- Second number.
Return value
The arctangent of the quotient of the given arguments.
Description
The Math.atan2()
method returns a numeric value between -π and π representing the angle theta of an (x, y)
point. This is the counterclockwise angle, measured in radians, between the positive X axis, and the point (x, y)
. Note that the arguments to this function pass the y-coordinate first and the x-coordinate second.
Math.atan2()
is passed separate x
and y
arguments, and Math.atan()
is passed the ratio of those two arguments.
Because atan2()
is a static method of Math
, you always use it as Math.atan2()
, rather than as a method of a Math
object you created (Math
is not a constructor).
Examples
Using Math.atan2()
Math.atan2(90, 15); // 1.4056476493802699 Math.atan2(15, 90); // 0.16514867741462683 Math.atan2(±0, -0); // ±PI. Math.atan2(±0, +0); // ±0. Math.atan2(±0, -x); // ±PI for x > 0. Math.atan2(±0, x); // ±0 for x > 0. Math.atan2(-y, ±0); // -PI/2 for y > 0. Math.atan2(y, ±0); // PI/2 for y > 0. Math.atan2(±y, -Infinity); // ±PI for finite y > 0. Math.atan2(±y, +Infinity); // ±0 for finite y > 0. Math.atan2(±Infinity, x); // ±PI/2 for finite x. Math.atan2(±Infinity, -Infinity); // ±3*PI/4. Math.atan2(±Infinity, +Infinity); // ±PI/4.
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript 1st Edition (ECMA-262) | Standard | Initial definition. Implemented in JavaScript 1.0. |
ECMAScript 5.1 (ECMA-262) The definition of 'Math.atan2' in that specification. |
Standard | |
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Math.atan2' in that specification. |
Standard | |
ECMAScript 2017 Draft (ECMA-262) The definition of 'Math.atan2' in that specification. |
Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |
See also
License
© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/javascript/reference/global_objects/math/atan2