For the Python version of this lesson, please click here.

The act of storing information in programming languages is important. Often, during simple or complex calculations, we need to reference some saved information at a later point. In programming languages, this storing of information is performed using variables. In this lesson, we will discuss how variables are used, and some basic math operations that can be utilized.

Variables

Variables can store and manipulate data in a programming language. Data values can be assigned to a variable using the assignment operator-- which is the equal sign (=). Once a value is assigned to the variable, it corresponds to that value unless it is re-assigned. Note: re-assignment touches upon mutability, which we'll cover later.

Let's see some code examples in JavaScript below.

Variables in JavaScript are commonly declared by using a var keyword, followed by a variable name, assignment operator (equals sign =), and a corresponding value.

1var number = 21;
2console.log(number); // prints 21

This will display the value 21, and this is verified by printing the variable value on the console.

In ES6, the variable declaration keywords let and const were introduced. We covered these keywords briefly in the last lesson. var has some weaknesses in terms of scope, and let and const are now preferred. For a deep dive of the difference between the three, check out this article.

1let number = 21;
2console.log(number); // prints 21

Let's test your variable knowledge with some short questions!

Basic Math Operations

In any programming language, one of the very basic tasks is to perform various mathematical calculations. These calculations can be performed by using the arithmetic operators that we have in basic maths! Using these operators combined with some other different aspects of the programming language can produce interesting results. A list of some common mathematical operators in programming languages is given below. The examples assume that the values of a and b are equal to 10.

Let's see these operations in action by looking at some code examples in JavaScript.

Math in JavaScript

Math operations in JavaScript can be performed by directly specifying a mathematical statement. If you're using any variables in the calculation, make sure to initialize them beforehand.

1var a = 20;
2var b = 10;
3
4console.log(a + b); // prints 30
5console.log(a - b); // prints 10
6console.log(a * b); // prints 200

You can also save these values in further variables, such as:

1var a = 20;
2var b = 10;
3var c = a + b;
4console.log(c); // prints 30

This is helpful in situations where you need to do more complex calculations, which may require multiple steps.

You must be wondering by now, are these the only mathematical operations supported by JavaScript?

The answer is no.

JavaScript supports an abundance of other operations, however, they are not provided using simple operators. These can be accessed through the JavaScript's built-in Math object. Simply use Math.<operator-name> and you can access more maths operators from there such as square root, floor and ceiling functions among many others. You will have to be careful with the spellings of these operators as they are built-in within the programming language.

Let's see some examples.

1var x = Math.floor(4.5);
2console.log(x); // prints 4
3
4var y = Math.sqrt(100);
5console.log(y); //prints 10

A comprehensive list of all operations provided by the JavaScript Math module is available here.

Summary

In this lesson, basic programming concepts about variables and mathematical operators were introduced. The most important thing about working with these basic concepts is to ensure that there are no syntax errors. Mastering these concepts is important as they will be the building blocks to further techniques in programming!

One Pager Cheat Sheet

• In this lesson, we will discuss how variables are used, as well as specific math operations in programming.
• A variable is a placeholder for storing data values in a programming language which can be assigned or re-assigned using the equal sign (=).
• Variables in JavaScript are declared by var, let, or const, and the preferred form for a deep dive is let and const, which offers improved scope over var.
• The code snippet is invalid due to the lack of a valid variable name after the var keyword.
• The value of c is assigned the same value as b, which is 10.
• Using aritmetic operators, one can perform basic math operations like addition, subtraction, multiplication, division, modulus and exponentiation in any programming language.
• Math operations in JavaScript can be performed by directly specifying a mathematical statement or by assigning the result to a variable c, such as var c = a + b for more complex calculations.
• JavaScript provides an abundance of mathematical operations through its Math object, and you can see examples of some of these with the available list at Mozilla Developer Network.
• The output of the code block is Math.sqrt(b) + a which results in 16.
• JavaScript comes with language-specific operators such as increment (++) and decrement (--) which work differently depending on whether they are pre- or post- placed in relation to a variable.
• The value of the variable c is decremented by 1 from 96 to 103 when --c is applied before the variable is returned.
• Basic programming concepts such as variables and mathematical operators are building blocks for developing further techniques, and it is important to ensure no syntax errors occur.