Math: Operators, Properties and Methods

Math: Operators, Properties and Methods
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JavaScript makes working with math easy. It provides us with the arithmetic operators you'd expect from a programming language, and offers us a cool Math library that does a lot of work for us so that we can focus on writing great code instead.

Math is easy.
Math is easy.

Arithmetic Operators

Here are some of the many arithmetic operators that allow you to manipulate numbers in JavaScript.

Addition

	
    // adding numbers
    var blueCars = 4;
    var redCars = 5;

    var totalCars = blueCars + redCars;

    console.log("I have " + totalCars + " cars!");
	
	
    I have 9 cars!
	

This is the shorthand way to add 1 to the value of a variable:

	
    var burritos = 4;
    burritos++; // adds 1

    console.log("I have " + burritos + " burritos!");
	
	
    I have 5 burritos!
	

This is the shorthand way to add an arbitrary number to the value of a variable:

	
    var books = 10;
    books += 20; // adds 20 books

    console.log("I have read " + books + " books!");
	
	
    I have read 30 books!
	

Subtraction

	
    // subtracting numbers
    var bobsApples = 13;
    var stolenApples = 7;

    var remainingApples = bobsApples - stolenApples;

    console.log("After getting robbed, he was left with " + remainingApples + " apples.");
	
	
    After getting robbed, he was left with 6 apples.
	

This is the shorthand way to subtract 1 from the value of a variable:

	
    var waterBottles = 4;
    waterBottles--; // subtracts 1

    console.log("I am down to " + waterBottles + " water bottles!");
	
	
    I am down to 3 water bottles!
	

This is the shorthand way to subtract an arbitrary number from the value of a variable:

	
    var apples = 50;
    apples -= 30; // subtracts 30 apples

    console.log("I have " + apples + " apples left!");
	
	
    I have 20 apples left!
	

Multiplication

	
    // multiplying numbers
    var tacosPerPerson = 3;
    var people = 20;

    var tacosNeeded = tacosPerPerson * people;

    console.log("We need " + tacosNeeded + " tacos for the party.");
	
	
    We need 60 tacos for the party.
	

This is the shorthand way to multiply the value of a variable:

	
    var boxes = 2;
    boxes *= 5; // multiplies the value by 5

    console.log("I have " + boxes + " boxes left!");
	
	
    I have 10 boxes left!
	

Division

	
    // dividing numbers
    var totalSkittles = 75;
    var kids = 5;

    var skittlesPerKid = totalSkittles / kids;

    console.log("Each kid gets " + skittlesPerKid + " skittles.");
	
	
    Each kid gets 15 skittles.
	

This is the shorthand way to divide a variable:

	
    var peanuts = 100;
    peanuts /= 20; // divides the value by 20

    console.log("I have " + peanuts + " peanuts left!");
	
	
    I have 5 peanuts left!
	

Modulus

	
    // modulus operator
    var people = 20;
    var peoplePerCar = 6;

    var peopleInLastCar = people % peoplePerCar;

    console.log("The last car will have " + peopleInLastCar + " people in it.");
	
	
    The last car will have 2 people in it.
	

This is the shorthand way to perform modulus:

	
    var slices = 45;
    slices %= 7; // does modulus 7

    console.log("I have " + slices + " slices leftover!");
	
	
    I have 3 slices leftover!
	

Order of Operations

Order of Operations, also known as PEMDAS, is at play here, including with the use of parentheses.

	
    // order of operations
    var x = (5 * 3) + 10 / 2;

    console.log("The value of x is " + x + ".");
	

Math Properties

JavaScript's Math library, among other things, gives us access to mathematical properties that are commonly used so that we do not need to implement this ourselves.

Euler's Number - Math.E

One of these constants is Euler's Number, via Math.E.

	
    var euler = Math.E;
    console.log(euler);
	
	
    2.718281828459045
	

Pi - Math.PI

Pi is the ratio of the circumference of a circle relative to its diameter, and is accessed in JavaScript using Math.PI.

	
    var pi = Math.PI;
    console.log(pi);
	
	
    3.141592653589793
	
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Math Methods

Likewise with properties, JavaScript also implements some commonly used mathematical methods that we can use anytime we want.

Absolute Number

Getting the absolute number is easy. Simple pass a number to Math.abs() and it will return what you expect.

	
    var a = 6;
    var b = -13;
    console.log("Absolute value of a is " + Math.abs(a) + ".");
    console.log("Absolute value of b is " + Math.abs(b) + ".");
	
	
    Absolute value of a is 6.
    Absolute value of b is 13.
	

Floor

The floor method rounds a number down to the nearest integer. Put a number inside Math.floor() and you're good to go.

	
    var decimal = 24.942;
    var floor = Math.floor(decimal);
    console.log("The value of floor is " + floor + ".");
	
	
    The value of ceiling is 24.
	

Ceiling

The ceiling method rounds a number up to the nearest integer. Put a number inside Math.ceil() and you're good to go.

	
    var decimal = 13.37;
    var ceiling = Math.ceil(decimal);
    console.log("The value of ceiling is " + ceiling + ".");
	
	
    The value of ceiling is 14.
	

Logarithm

You can get the natural logarithm of a number using the Math.log() method.

	
    var number = Math.log(1);
    console.log("The value of number is " + number + ".");
	
	
    The value of number is 0.
	

Maximum

You can get the maximum of two numbers using the Math.max() method.

	
    var number = Math.max(14, 349);
    console.log("The value of number is " + number + ".");
	
	
    The value of number is 349.
	

Minimum

You can get the minimum of two numbers using the Math.min() method.

	
    var number = Math.min(53, 94);
    console.log("The value of number is " + number + ".");
	
	
    The value of number is 53.
	

Power

You can take the power of a number by using Math.pow().

	
    var number = Math.pow(3, 2);
    console.log("The value of number is " + number + ".");
	
	
    The value of number is 9.
	

Random

To get a random number in JavaScript, there's a Math.random() method for that. By itself, it just returns a number between 0 and 1.

	
    var random = Math.random();
    console.log("The value of random is " + random + ".");
	
	
    The value of random is 0.2156683652500082.
	

However, you can manipulate this fact to get a random number between two other numbers, like this:

	
    function randomBetween(min, max) {
        return Math.floor(Math.random() * (max - min + 1)) + min;
    }
    var random = randomBetween(5, 25);
    console.log("The value of random is " + random + ".");
	
	
    The value of random is 15.
	

Round

You can round a number to the nearest integer using Math.round().

	
    var rounded = Math.round(3.1459);
    console.log("The value of rounded is " + rounded + ".");
	
	
    The value of rounded is 3.
	

Square Root

You can take the square root of a number with Math.sqrt().

	
    var root = Math.sqrt(49);
    console.log("The value of root is " + root + ".");
	
	
    The value of root is 7.
	

That's all we got for math! 🤓🤓🤓