JavaScript Syntax

JavaScript Comments

Comments are used to explain the code and make it more readable.

Comments are created in JavaScript using the // syntax.

To create a multi-line comment, use the /* and */ syntax.

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JavaScript Variables

Variables are declared with the let or const keywords.

NOTE: A const variable MUST be assigned a value when it is declared.

NOTE: A variable name CANNOT contain hyphens, as in JavaScript they are reserved for subtraction. For example, let variable-name = 10; is invalid, but let variableName = 10; is valid.

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JavaScript Keywords

Keywords are reserved words that are used to declare variables, functions, and other elements in JavaScript.

Keyword	Description
let	Declares a variable
const	Declares a constant
var	Declares a variable (NOT RECOMMENDED FOR MODERN JS)
function	Declares a function
return	Returns a value from a function
if	Checks if a condition is true
else	Executes code if the condition is false
while	Executes code while a condition is true
for	Executes code a specified number of times
break	Exits a loop
continue	Skips to the next iteration of a loop
try	Executes code that may throw an error
catch	Executes code if an error is thrown

NOTE: There are many more keywords in JavaScript, but these are the most commonly used.