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[JavaScript] Math

category: Website | course: JavaScript | difficulty:

To finish the part on Numbers, let’s have a look at the Math object. It has a great deal of useful methods, like the sine and cosine functions, as well as important mathematical constants.

How to Use It

Calling it is as simple as writing Math.someMethod(arguments)

The Math object is created and maintained by JavaScript itself, which means you don’t have to declare it, and it can be accessed from anywhere. Calling such a method doesn’t change the actual number(s) you put into it; it simply generates a number using them, and gives it to you to do whatever you want with it.

var x = 0;
var y = Math.cos(x); // y is 1, but x is still zero

Manipulating Numbers

Method

Description

Math.abs(x)

Absolute value of x

Math.round(x)

Rounds x to the nearest integer

Math.floor(x)

Rounds x down to the nearest integer

Math.ceil(x)

Rounds x up to the nearest integer

console.log(Math.floor(1.5)); //Prints 1
console.log(Math.ceil(1.5)); //Prints 2
console.log(Math.round(1.5)); //Prints 2

Finding Values

Method

Description

Math.max(x1,x2,…,xn)

Maximum; returns number with highest value

Math.min(x1,x2,…,xn)

Minimum; returns number with lowest value

Math.random()

Random number between 0 and 1

Math.pow(x,y)

x to the power of y

Math.exp(x)

Returns the value of Ex

Math.log(x)

Returns the value of ln(x)

console.log(Math.min(1,-5,3,10,50)); //Prints -5

Math.random() generates a random number between 0 (inclusive) and 1 (exclusive). If you, for example, want a random value between 0 and 100, simply multiply this value by one hundred.

Trigonometry

Method

Description

Math.sin(x)

Sine of x

Math.cos(x)

Cosine of x

Math.tan(x)

Tangent of x

Math.asin(x)

Arcsine of x

Math.acos(x)

Arccosine of x

Math.atan(x)

Arctangent of x, as numeric value between –PI/2 and PI/2 radians

Math.atan2(x,y)

Arctangent of the quotient of its arguments

Math.sqrt(x)

Square root of x

var x = Math.sin(0) + Math.cos(0) + Math.sqrt(4); // x is 3

JavaScript works with radians, not degrees!

Constants

Method

Description

Math.E

Euler’s number

Math.PI

PI (π)

Math.SQRT2

Square root of 2

Math.SQRT1_2

Square root of 1/2

Math.LN2

Natural logarithm of 2

Math.LN10

Natural logarithm of 10

Math.LOG2E

Base 2 logarithm of Euler’s number

Math.LOG10E

Base 10 logarithm of Euler’s number

console.log(Math.PI); //Prints 3.141592653589793
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