Javascript Syntax

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If you’re looking to learn how to write JavaScript, you’ve come to the right place.

Each programming language has its own rules, just like English. Think about it. When you were in elementary school, you learned grammar rules to structure sentences.

Much like English, programming languages ‚Äã‚Äãfollow rules to ensure that everyone can understand what is being said. Imagine if we could all create our own rules when using English. No one could communicate. Likewise, programming languages ‚Äã‚Äãare strict on the rules so that the code you write can be executed.

In this guide, we’ll cover JavaScript syntax. Syntax refers to the set of rules that define how code is written in JavaScript.

Why is syntax important?

In JavaScript, you must follow certain syntax rules. For example, if you don’t close a hook after opening one, an error will be returned. The computer cannot continue to run your program because it does not understand what you are telling it to do.

This deserves an important distinction between computers and humans: while humans may be able to identify the occasional error and skip it, computers cannot do the same when executing code in any programming language. This is why it is important to write code using the syntax of the programming language you are working with.

The syntax also makes your code more readable. When everyone uses the same syntax, it is easy to interpret each other’s programs. Just like in English, once you know the basic rules there are no more lines of code that you cannot read.

In this guide, we’ll focus on the following syntax features:

  • Whitespace
  • Naming of variables
  • Withdrawal
  • Comments
  • Semicolon

Let’s go!


Programmers are constantly discussing whitespaces. It is a very controversial subject. Putting these debates aside for a minute, there is one key rule you must remember when it comes to JavaScript syntax: you should have spaces between variables and before and after brackets

Suppose you write a loop for:

This loop prints all numbers between 0 and 4. as you can see it There is a space between our and the support for opening our loop. There is a space between our closing brace (() and the opening brace ({). There is also a space between all statements in parentheses:

  • var i = 0;
  • i <4;

When assigning a variable outside of a loop, you will use the same approach:

var biscuit = "raspberry Chocolate Chip";

Adding spaces between yo Our variables make it easier to read code creation.

Unlike other programming languages, you can write a single line JavaScript program. Not a good idea - think how hard it would be to read your code - but you can still do it.

Any statement that is inside a block of code - such as a conditional if statement or a class - must be indented. Indent refers to the add two spaces, four spaces or a tab at the beginning t code. There is a lot of debate among programmers as to which is best, but as long as you keep your code consistent, you won’t have a problem.

Here is an indented for loop:

You can see that the term console.log () has been indented with a tab. This is because it is contained in our braces. This helps distinguish the content of our for loop from the rest of our code. If we had another block of code in our code, like an if statement, we would indent its contents further:

This code prints the value of i if it is equal to three. Otherwise nothing happens. In this snippet, our if statement is in removal of a tab because it is in our for loop. Our console.log () statement is indented by two tabs because it is contained in our statement if, which in turn is contained in our for statement.


Comments are statements written by the developers, for the developers. technically, they are read by JavaScript, but will not be executed.

Lo The purpose of comments is to help developers keep track of their code. If you are implementing a complex function, you can write some comments so that you know what each part of the function does. Comments are often used in collaborative projects as although every developer can understand a program, even if they haven’t written themselves

in JavaScript, comments are written using double slashes , followed by the comment: ..

All subsequent characters after the double slash are treated as a comment. To create a multiline comment, you can use this syntax:

Any text between / * and * / will be ignored by the JavaScript compiler.

Naming variables

There are many different ways to name a variable. The three most common methods use upper and lower case letters and underscores.

In JavaScript, most developers prefer to use lowercase letters to name variables:

firstName, surname, isAdmin

The variable declaration looks like JavaScript like this:

var firstname = "Tony";

we follow the type of variable you use (in this case var) by the name of the variable, then by an equal sign, then by the value you want to store in the variable.

The first word of a variable must start with a lowercase letter, even if the variable is only one word long. The second word and all subsequent words must start with an uppercase letter, as you can see above.

Although you can write variables using other methods (such as "first_name" in underscore or "FirstName" in uppercase camel), it is not common to do so. in JavaScript.

Variables in JavaScript are case sensitive . this means that firstname and firstname, while containing the same basic characters, would be treated differently.

There are a few words called "reserved words‚" that you cannot use as variable names . these are words they have one. special function in JavaScript for example, you cannot name a variable "class" or "for" because they are already used in language


You can find a list of reserved JavaScript keywords on target Mozilla Developer Network .


In English, each sentence ends with a period ; a point. tells you when to stop reading one sentence and start another. If you think back to your elementary school years, you’ve probably been told that sentences are a place to pause and catch your breath.

Computer programs. don’t "don’t need to catch your breath, but they do need to know how instructions are broken down into a program in JavaScript, most instructions end with a semicolon:

var cookie = "Chocolate fondant"

It is not necessary to specify a semicolon after each declaration block . These are statements like class, switch, do, if, and for. These statements use curly braces to store their code:

In this code, you can see that we ended our return statement with a semicolon. It is because it is in our function. Our function does not end with a semicolon.


There are many rules in the JavaScript programming language. Each of these rules ensures that you are writing code that you and the browser can read. If you are working in a team, it is especially important to follow the rules of JavaScript syntax.

Here is a summary of the main rules we covered:

You are now ready to start coding in JavaScript as a professional developer !

👻 Read also: what is the best laptop for engineering students?

We hope this article has helped you to resolve the problem. Apart from Javascript Syntax, check other __main__ Python module-related topics.

Want to excel in Python? See our review of the best Python online courses 2023. If you are interested in Data Science, check also how to learn programming in R.

By the way, this material is also available in other languages:

Dmitry Emmerson

Munchen | 2023-01-31

Thanks for explaining! I was stuck with Javascript Syntax for some hours, finally got it done 🤗. I am just not quite sure it is the best method

Xu Ungerschaft

San Francisco | 2023-01-31

Thanks for explaining! I was stuck with Javascript Syntax for some hours, finally got it done 🤗. Checked yesterday, it works!

Javier Krasiko

Texas | 2023-01-31

I was preparing for my coding interview, thanks for clarifying this - Javascript Syntax in Python is not the simplest one. Will use it in my bachelor thesis


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