Learn JS #21

JavaScript Math Object

The JavaScript Math object allows you to perform mathematical tasks on numbers.

Example

Math.PI;

The Math Object

Unlike other objects, the Math object has no constructor.

The Math object is static.

All methods and properties can be used without creating a Math object first.


Math Properties (Constants)

The syntax for any Math property is : Math.property.

JavaScript provides 8 mathematical constants that can be accessed as Math properties:

Example

Math.E        // returns Euler's number
Math.PI       // returns PI
Math.SQRT2    // returns the square root of 2
Math.SQRT1_2  // returns the square root of 1/2
Math.LN2      // returns the natural logarithm of 2
Math.LN10     // returns the natural logarithm of 10
Math.LOG2E    // returns base 2 logarithm of E
Math.LOG10E   // returns base 10 logarithm of E

Math Methods

The syntax for Math any methods is : Math.method(number)


Number to Integer

There are 4 common methods to round a number to an integer:

Math.round(x) Returns x rounded to its nearest integer
Math.ceil(x) Returns x rounded up to its nearest integer
Math.floor(x) Returns x rounded down to its nearest integer
Math.trunc(x) Returns the integer part of x

Math.round()

Math.round(x) returns the nearest integer:

Examples

Math.round(4.6);

Math.round(4.5);

Math.round(4.4);

Math.ceil()

Math.ceil(x) returns the value of x rounded up to its nearest integer:

Example

Math.ceil(4.9);
Math.ceil(4.7);
Math.ceil(4.4);
Math.ceil(4.2);
Math.ceil(-4.2);

Math.floor()

Math.floor(x) returns the value of x rounded down to its nearest integer:

Example

Math.floor(4.9);
Math.floor(4.7);
Math.floor(4.4);
Math.floor(4.2);
Math.floor(-4.2);

Math.trunc()

Math.trunc(x) returns the integer part of x:

Example

Math.trunc(4.9);
Math.trunc(4.7);
Math.trunc(4.4);
Math.trunc(4.2);
Math.trunc(-4.2);

Math.sign()

Math.sign(x) returns if x is negative, null or positive:

Example

Math.sign(-4);
Math.sign(0);
Math.sign(4);

Math.pow()

Math.pow(x, y) returns the value of x to the power of y:

Example

Math.pow(82);

Math.sqrt()

Math.sqrt(x) returns the square root of x:

Example

Math.sqrt(64);

Math.abs()

Math.abs(x) returns the absolute (positive) value of x:

Example

Math.abs(-4.7);

Math.sin()

Math.sin(x) returns the sine (a value between -1 and 1) of the angle x (given in radians).

If you want to use degrees instead of radians, you have to convert degrees to radians:

Angle in radians = Angle in degrees x PI / 180.

Example

Math.sin(90 * Math.PI / 180);     // returns 1 (the sine of 90 degrees)

Math.cos()

Math.cos(x) returns the cosine (a value between -1 and 1) of the angle x (given in radians).

If you want to use degrees instead of radians, you have to convert degrees to radians:

Angle in radians = Angle in degrees x PI / 180.

Example

Math.cos(0 * Math.PI / 180);     // returns 1 (the cos of 0 degrees)

Math.min() and Math.max()

Math.min() and Math.max() can be used to find the lowest or highest value in a list of arguments:

Example

Math.min(01503020, -8, -200);

Example

Math.max(01503020, -8, -200);

Math.random()

Math.random() returns a random number between 0 (inclusive), and 1 (exclusive):

Example

Math.random();

You will learn more about Math.random() in the next chapter of this tutorial.


The Math.log() Method

Math.log(x) returns the natural logarithm of x.

The natural logarithm returns the time needed to reach a certain level of growth:

Examples

Math.log(1);

Math.log(2);

Math.log(3);

Math.E and Math.log() are twins.

How many times must we multiply Math.E to get 10?

Math.log(10);

The Math.log2() Method

Math.log2(x) returns the base 2 logarithm of x.

How many times must we multiply 2 to get 8?

Math.log2(8);

The Math.log10() Method

Math.log10(x) returns the base 10 logarithm of x.

How many times must we multiply 10 to get 1000?

Math.log10(1000);

JavaScript Math Methods

Method Description
abs(x) Returns the absolute value of x
acos(x) Returns the arccosine of x, in radians
acosh(x) Returns the hyperbolic arccosine of x
asin(x) Returns the arcsine of x, in radians
asinh(x) Returns the hyperbolic arcsine of x
atan(x) Returns the arctangent of x as a numeric value between -PI/2 and PI/2 radians
atan2(y, x) Returns the arctangent of the quotient of its arguments
atanh(x) Returns the hyperbolic arctangent of x
cbrt(x) Returns the cubic root of x
ceil(x) Returns x, rounded upwards to the nearest integer
cos(x) Returns the cosine of x (x is in radians)
cosh(x) Returns the hyperbolic cosine of x
exp(x) Returns the value of Ex
floor(x) Returns x, rounded downwards to the nearest integer
log(x) Returns the natural logarithm (base E) of x
max(x, y, z, …, n) Returns the number with the highest value
min(x, y, z, …, n) Returns the number with the lowest value
pow(x, y) Returns the value of x to the power of y
random() Returns a random number between 0 and 1
round(x) Rounds x to the nearest integer
sign(x) Returns if x is negative, null or positive (-1, 0, 1)
sin(x) Returns the sine of x (x is in radians)
sinh(x) Returns the hyperbolic sine of x
sqrt(x) Returns the square root of x
tan(x) Returns the tangent of an angle
tanh(x) Returns the hyperbolic tangent of a number
trunc(x) Returns the integer part of a number (x)

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