Understanding JavaScript Syntax and Comments

There is a famous quote by John Woods - "Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live." It highlights the importance of writing clean, well-organized code that is easy for other programmers to understand and maintain. Proper syntax and commenting are essential for achieving this goal, as they provide clarity and context to the code, making it easier for others to read, modify, and debug.

To be able to write effective JavaScript code, it is important to have a good understanding of its syntax and comments.

JavaScript Syntax

Syntax in programming refers to the set of rules that define the structure, format, and organization of the instructions or statements that make up a programming language. These rules determine how programmers can write code in a particular language and how the computer can understand and execute that code.

JavaScript code is made up of a series of statements. A statement is a single line of code that performs an action. For example, the following statement assigns a value of 5 to the variable "x":


In JavaScript, statements are separated by semicolons (;). However, it is not always necessary to include a semicolon at the end of each statement. JavaScript is a "loosely typed" language, meaning that it is not necessary to declare the type of a variable before using it. Variables can be declared using the "var" keyword.

JavaScript has several types of data, including numbers, strings, and boolean values. To define a string, you can use either single quotes (') or double quotes ("). For example:


To define a boolean value, you can use the keywords "true" or "false". For example:


JavaScript also has operators, such as + (addition), - (subtraction), * (multiplication), and / (division). These can be used to perform arithmetic operations on numbers, as well as concatenate strings. For example:


JavaScript Comments

Comments are an important aspect of any programming language. They allow you to explain what your code does, and make it easier for others to understand your code. JavaScript supports two types of comments: single-line comments and multi-line comments.

Single-line comments start with two forward slashes (//). Any text that follows the slashes will be ignored by the JavaScript interpreter. For example:


Multi-line comments start with a forward slash followed by an asterisk (/), and end with an asterisk followed by a forward slash (/). Any text between the starting and ending symbols will be ignored by the JavaScript interpreter. For example:

This is a multi-line comment
that spans multiple lines

There are several reasons why JavaScript comments are important:

  1. Clarity: Comments can make code easier to read and understand by providing additional context and explanations for complex logic or algorithms.
  2. Collaboration: Comments can help other developers understand what your code does and why, making it easier for them to collaborate with you on a project.
  3. Debugging: Comments can also be used to temporarily disable portions of code for debugging purposes without actually deleting them.
  4. Documentation: Comments can be used to document important information about a function or a variable, such as its purpose, parameters, or expected behavior.


Syntax refers to the set of rules that define the structure, format, and organization of the code, while comments serve to provide context, clarity, and documentation for the code. By adhering to proper syntax and utilizing comments effectively, developers can create code that is easier to read, modify, debug, and collaborate on, ultimately leading to more efficient and successful software development projects.

Module 1: JavaScript FundamentalsUnderstanding JavaScript Syntax and Comments

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