Converting degree to radian in JavaScript

Converting degrees to radians is a common mathematical operation in JavaScript, especially when working with trigonometric functions or graphics programming.

Understanding Radians

The radian is the standard unit for measuring angles in mathematics. One complete circle equals 2? radians, which is equivalent to 360 degrees. This means ? radians equals 180 degrees.

The Conversion Formula

To convert degrees to radians, multiply the degree value by ?/180:

radians = degrees × (? / 180)

Method 1: Using the Standard Formula

const degreeToRadian = (degree) => {
    const factor = Math.PI / 180;
    const rad = degree * factor;
    return rad;
};

// Test with common angles
console.log("90° =", degreeToRadian(90), "radians");
console.log("180° =", degreeToRadian(180), "radians");
console.log("360° =", degreeToRadian(360), "radians");

90° = 1.5707963267948966 radians
180° = 3.141592653589793 radians
360° = 6.283185307179586 radians

Method 2: Simplified One-liner

const toRadians = (degrees) => degrees * (Math.PI / 180);

console.log("45° =", toRadians(45));
console.log("270° =", toRadians(270));

45° = 0.7853981633974483
270° = 4.71238898038469

Common Degree to Radian Conversions

Practical Example: Circle Animation

function calculateCirclePoints(radius, numPoints) {
    const points = [];
    const angleStep = 360 / numPoints; // degrees between each point
    
    for (let i = 0; i  {
    console.log(`${point.degrees}° (${point.radians} rad): (${point.x}, ${point.y})`);
});

Points on circle:
0° (0.000 rad): (10.00, 0.00)
90° (1.571 rad): (0.00, 10.00)
180° (3.142 rad): (-10.00, 0.00)
270° (4.712 rad): (-0.00, -10.00)

Conclusion

Converting degrees to radians in JavaScript is straightforward using the formula `degrees × (? / 180)`. This conversion is essential for trigonometric calculations and graphics programming where precise angle measurements are required.