JavaScript atan2

Introduction

The atan2() method in JavaScript returns the arctangent of a given pair of coordinates (x,y). It is similar to the Math.atan() method, but takes both the x and y coordinates as arguments. It returns the angle in radians between -π and π radians, indicating the counterclockwise rotation of a vector from the positive x-axis to the vector (x,y).

Syntax

The syntax for the atan2() method is as follows:

Math.atan2(y, x)

where x is the horizontal coordinate and y is the vertical coordinate of the point.

Examples

Let's look at some examples to better understand how to use the atan2() method.

Example 1: Basic Usage

const x = 4;
const y = 2;

const angle = Math.atan2(y, x);

console.log(angle);
// expected output: 0.4636476090008061

In this example, we have a point (4, 2) and we want to find the angle between the positive x-axis and the vector from the origin to that point. We use the atan2() method to calculate the angle and store it in the angle variable. We then log the angle to the console.

Example 2: Negative Coordinates

const x = -3;
const y = 5;

const angle = Math.atan2(y, x);

console.log(angle);
// expected output: 2.0344439357957027

In this example, we have a point (-3, 5) which lies in the second quadrant. We use the atan2() method to calculate the angle between the positive x-axis and the vector from the origin to that point. Since the x coordinate is negative, the angle will be greater than π/2 radians. We store the angle in the angle variable and log it to the console.

Example 3: Using Degrees

const x = 1;
const y = 1;

const angleRadians = Math.atan2(y, x);
const angleDegrees = angleRadians * 180 / Math.PI;

console.log(angleDegrees);
// expected output: 45

In this example, we have a point (1, 1) and we want to find the angle between the positive x-axis and the vector from the origin to that point. We use the atan2() method to calculate the angle in radians and store it in the angleRadians variable. We then convert the angle to degrees by multiplying it by 180/π and store it in the angleDegrees variable. We log the angle in degrees to the console.

Conclusion

In conclusion, the atan2() method in JavaScript is a useful tool for calculating the angle between a point and the positive x-axis. It takes both the x and y coordinates as arguments and returns the angle in radians between -π and π radians. By using the atan2() method, we can easily determine the correct angle for our calculations.