JavaScript Math atan2() is a built-in function that returns an arctangent of the quotient of its arguments. The atan2() method returns a numeric value between -Π and Π representing the angle theta of the (x, y) point and the positive x-axis.
To find the arctangent quotient of two passed arguments in JavaScript, use the Math.atan2() method.
See the following figure.
Since atan2() is a static method of Math, it can be used without creating an object.
Syntax
Math.atan2(y,x)
Parameter(s)
The variables y and x, whose arctangent quotient is to be determined.
Return Value
The arctangent quotient is in the range from -pi to pi radians.
See the following figure.
Example 1
The following example demonstrates the use of the atan2() method.
var x = 5;
var y = 4;
console.log(Math.atan2(y, x));
var x = 90;
var y = 15;
console.log(Math.atan2(y, x));
var x = 15;
var y = 90;
console.log(Math.atan2(y, x));
Output
0.6747409422235527
0.16514867741462683
1.4056476493802699
Example 2
The following example demonstrates the case where an empty value is passed.
var x;
var y;
console.log(Math.atan2(x, y));
console.log(Math.atan2());
Output
NaN
NaN
Example 3
If the second parameter is passed as negative zero, and the first argument is ±0, the method returns pi with the same sign as the first argument.
var x = -0;
var a = 0;
var b = -0;
console.log(Math.atan2(a, x));
console.log(Math.atan2(b, x));
Output
3.141592653589793
-3.141592653589793
That’s it.