constants
Math.PI
The ratio of a circle's circumference to its diameter, approximately 3.141592653589793. A read-only numeric property, not a function.
Math.PIParameters & edge cases
| Case | Behavior |
|---|---|
| precision | Math.PI is a double-precision approximation, not exact π — small trig errors are unavoidable |
| degrees to radians | Multiply degrees by (Math.PI / 180) |
| radians to degrees | Multiply radians by (180 / Math.PI) |
Examples
console.log(Math.PI); // 3.141592653589793The stored value.
console.log(Math.PI * 2); // 6.2831853071795862π — one full turn in radians (a.k.a. τ).
console.log(180 / Math.PI); // 57.29577951308232Degrees per radian — used for radians→degrees conversion.
console.log(Math.PI * r * r); // area of a circleClassic πr² formula.
Gotcha
Math.PI is only accurate to ~15-17 decimal digits. Because of that, Math.sin(Math.PI) is ≈1.22e-16, not 0 — never compare trig outputs with strict equality.
Related
Math.E
Euler's number, the base of the natural logarithm, approximately 2.718281828459045. A read-only numeric property.
Math.sin
Returns the sine of an angle expressed in radians. Result is always in the range [-1, 1].
Math.cos
Returns the cosine of an angle expressed in radians. Result is always in [-1, 1].