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Cover image for JavaScript Made Easy: Part 4
David Tetreau
David Tetreau

Posted on • Updated on

JavaScript Made Easy: Part 4

For this post, we will go over various topics such as comments, assignment operators, and arithmetic operators. As always, open up a repl and code along with this post. You learn more by doing it yourself, and you will build muscle memory. Log all of these operations to the console in your repl and use comments to reinforce what you are doing.


Comments are fairly easy to understand. There are two types of comments in JavaScript. The first is a single-line comment. The second is a multi-line comment. Here are some examples:

// This is a single-line comment.

This is a multi-line comment.
Everything inside of this comment
will not be run. You can also 
use comments for not only notes, 
but you can comment out a block of
code that you want to leave out but
not delete
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Assignment Operators

There are several different types of operators in JavaScript:
Assignment operators assign a value to a variable. You learned about this in previous posts.

const currentLesson = 4; //assignment operator
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Arithmetic Operators

  • Addition

The addition operator is used for adding numbers, adding booleans, adding variables, and for combining strings together.

// expected result: 4
2 + 2

// expected result: 3
2 + true

expected result: "I am a Developer"
Notice that there had to be a space 
added at the end of the first string
'I am a ' + 'Developer'

//expected result: '2001 is my graduation year'
2001 + ' is my graduation year'
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  • Multiplication

The multiplication operator multiplies numbers or numbers stored in variables. Here is an example:

//multiplying numbers
5 * 3 //equals 15 

//multiplying variables
const number1 = 5;
const number2 = 3; 
const number3 = number1 * number2 // equals 15
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  • Other operators that can be used to do arithmetic the same way are:
5 - 5 //subtraction|

expected output is 81
same as 3 to the 4th power
3 ** 4

1 / 2 //division

returns the remainder 
after division
12 % 5 

++ // increment (increases a number by 1)

-- // decrement (decreases a number by 1)
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I hope you have enjoyed this post! Please check out the entire "JavaScript Made Easy" series by David Tetreau. There will be a new post daily.

Discussion (4)

jonrandy profile image
Jon Randy

Your explanation of ++ and -- is overly simplistic. As you rightly say, they increment and decrement a variable by 1 - but the position of operator changes what is returned:

// Contrast this
a = 1
b = a++
console.log(a, b) // 2 1

// with this
a = 1
b = ++a
console.log(a, b) // 2 2
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The postfix version will return a then increment it, whereas the prefix version will increment a then return its new value.

dtetreau profile image
David Tetreau Author • Edited on

Thank you for the feedback! I added a section to the next post after I saw your recommendation. Thanks again!

adetolayemi profile image

Thank you Mr David for this effort. Your lesson is the first among many that held me down to the end! My thirst for more lessons from you needs to be quenched sir. When are you going to release more lessons?

dtetreau profile image
David Tetreau Author

I post every day! Thanks for the kind words!