Math
Math
is an object with data properties and methods for processing numbers. You can see it as a poor man’s module: It was created long before JavaScript had modules.
Math.E: number
[ES1]
Euler’s number, base of the natural logarithms, approximately 2.7182818284590452354.
Math.LN10: number
[ES1]
The natural logarithm of 10, approximately 2.302585092994046.
Math.LN2: number
[ES1]
The natural logarithm of 2, approximately 0.6931471805599453.
Math.LOG10E: number
[ES1]
The logarithm of e to base 10, approximately 0.4342944819032518.
Math.LOG2E: number
[ES1]
The logarithm of e to base 2, approximately 1.4426950408889634.
Math.PI: number
[ES1]
The mathematical constant π, ratio of a circle’s circumference to its diameter, approximately 3.1415926535897932.
Math.SQRT1_2: number
[ES1]
The square root of 1/2, approximately 0.7071067811865476.
Math.SQRT2: number
[ES1]
The square root of 2, approximately 1.4142135623730951.
Math.cbrt(x: number): number
[ES6]
Returns the cube root of x
.
> Math.cbrt(8)2
Math.exp(x: number): number
[ES1]
Returns ex
(e being Euler’s number). The inverse of Math.log()
.
> Math.exp(0)1
> Math.exp(1) === Math.Etrue
Math.expm1(x: number): number
[ES6]
Returns Math.exp(x)-1
. The inverse of Math.log1p()
. Very small numbers (fractions close to 0) are represented with a higher precision. Therefore, this function returns more precise values whenever .exp()
returns values close to 1.
Math.log(x: number): number
[ES1]
Returns the natural logarithm of x
(to base e, Euler’s number). The inverse of Math.exp()
.
> Math.log(1)0
> Math.log(Math.E)1
> Math.log(Math.E ** 2)2
Math.log1p(x: number): number
[ES6]
Returns Math.log(1 + x)
. The inverse of Math.expm1()
. Very small numbers (fractions close to 0) are represented with a higher precision. Therefore, you can provide this function with a more precise argument whenever the argument for .log()
is close to 1.
Math.log10(x: number): number
[ES6]
Returns the logarithm of x
to base 10. The inverse of 10 ** x
.
> Math.log10(1)0
> Math.log10(10)1
> Math.log10(100)2
Math.log2(x: number): number
[ES6]
Returns the logarithm of x
to base 2. The inverse of 2 ** x
.
> Math.log2(1)0
> Math.log2(2)1
> Math.log2(4)2
Math.pow(x: number, y: number): number
[ES1]
Returns x
y
, x
to the power of y
. The same as x ** y
.
> Math.pow(2, 3)8
> Math.pow(25, 0.5)5
Math.sqrt(x: number): number
[ES1]
Returns the square root of x
. The inverse of x ** 2
.
> Math.sqrt(9)3
Rounding means converting an arbitrary number to an integer (a number without a decimal fraction). The following functions implement different approaches to rounding.
Math.ceil(x: number): number
[ES1]
Returns the smallest (closest to −∞) integer i
with x
≤ i
.
> Math.ceil(2.1)3
> Math.ceil(2.9)3
Math.floor(x: number): number
[ES1]
Returns the largest (closest to +∞) integer i
with i
≤ x
.
> Math.floor(2.1)2
> Math.floor(2.9)2
Math.round(x: number): number
[ES1]
Returns the integer that is closest to x
. If the decimal fraction of x
is .5
then .round()
rounds up (to the integer closer to positive infinity):
> Math.round(2.4)2
> Math.round(2.5)3
Math.trunc(x: number): number
[ES6]
Removes the decimal fraction of x
and returns the resulting integer.
> Math.trunc(2.1)2
> Math.trunc(2.9)2
Tbl. 12 shows the results of the rounding functions for a few representative inputs.
-2.9 |
-2.5 |
-2.1 |
2.1 |
2.5 |
2.9 |
|
---|---|---|---|---|---|---|
Math.floor |
-3 |
-3 |
-3 |
2 |
2 |
2 |
Math.ceil |
-2 |
-2 |
-2 |
3 |
3 |
3 |
Math.round |
-3 |
-2 |
-2 |
2 |
3 |
3 |
Math.trunc |
-2 |
-2 |
-2 |
2 |
2 |
2 |
All angles are specified in radians. Use the following two functions to convert between degrees and radians.
function degreesToRadians(degrees) {
return degrees / 180 * Math.PI;
}.equal(degreesToRadians(90), Math.PI/2);
assert
function radiansToDegrees(radians) {
return radians / Math.PI * 180;
}.equal(radiansToDegrees(Math.PI), 180); assert
Math.acos(x: number): number
[ES1]
Returns the arc cosine (inverse cosine) of x
.
> Math.acos(0)1.5707963267948966
> Math.acos(1)0
Math.acosh(x: number): number
[ES6]
Returns the inverse hyperbolic cosine of x
.
Math.asin(x: number): number
[ES1]
Returns the arc sine (inverse sine) of x
.
> Math.asin(0)0
> Math.asin(1)1.5707963267948966
Math.asinh(x: number): number
[ES6]
Returns the inverse hyperbolic sine of x
.
Math.atan(x: number): number
[ES1]
Returns the arc tangent (inverse tangent) of x
.
Math.atanh(x: number): number
[ES6]
Returns the inverse hyperbolic tangent of x
.
Math.atan2(y: number, x: number): number
[ES1]
Returns the arc tangent of the quotient y/x.
Math.cos(x: number): number
[ES1]
Returns the cosine of x
.
> Math.cos(0)1
> Math.cos(Math.PI)-1
Math.cosh(x: number): number
[ES6]
Returns the hyperbolic cosine of x
.
Math.hypot(...values: number[]): number
[ES6]
Returns the square root of the sum of the squares of values
(Pythagoras’ theorem):
> Math.hypot(3, 4)5
Math.sin(x: number): number
[ES1]
Returns the sine of x
.
> Math.sin(0)0
> Math.sin(Math.PI / 2)1
Math.sinh(x: number): number
[ES6]
Returns the hyperbolic sine of x
.
Math.tan(x: number): number
[ES1]
Returns the tangent of x
.
> Math.tan(0)0
> Math.tan(1)1.5574077246549023
Math.tanh(x: number): number;
[ES6]
Returns the hyperbolic tangent of x
.
Math.abs(x: number): number
[ES1]
Returns the absolute value of x
.
> Math.abs(3)3
> Math.abs(-3)3
> Math.abs(0)0
Math.clz32(x: number): number
[ES6]
Counts the leading zero bits in the 32-bit integer x
. Used in DSP algorithms.
> Math.clz32(0b01000000000000000000000000000000)1
> Math.clz32(0b00100000000000000000000000000000)2
> Math.clz32(2)30
> Math.clz32(1)31
Math.max(...values: number[]): number
[ES1]
Converts values
to numbers and returns the largest one.
> Math.max(3, -5, 24)24
Math.min(...values: number[]): number
[ES1]
Converts values
to numbers and returns the smallest one.
> Math.min(3, -5, 24)-5
Math.random(): number
[ES1]
Returns a pseudo-random number n
where 0 ≤ n
< 1.
/** Returns a random integer i with 0 <= i < max */
function getRandomInteger(max) {
return Math.floor(Math.random() * max);
}
Math.sign(x: number): number
[ES6]
Returns the sign of a number:
> Math.sign(-8)-1
> Math.sign(0)0
> Math.sign(3)1