JavaScript Statements

In JavaScript, a statement is a syntactic unit of code that expresses an action to be carried out. Statements form the building blocks of a JavaScript program, instructing the interpreter or browser to perform specific actions such as declaring variables, making decisions, or iterating over collections. Each statement ends with a semicolon (;), though in many cases, JavaScript allows you to omit the semicolon if the statement is on a single line.

Declaring Variables

• var: Declares a variable, optionally initializing it to a value.
  
  
• let: Declares a block-scope local variable, optionally initializing it to a value.
  
  
• const: Declares a read-only named constant.
  
  
• function: Declares a function with specified parameters.
  
  
• class: Declares a class.
  
  
  

Control Flow

• return: Specifies the value to be returned by a function.
  
  
• break: Terminates the current loop, switch, or label statement and transfers control to the statement following the terminated statement.
  
  
• continue: Terminates the execution of the statements in the current iteration of the loop and continues with the next iteration.
  
  
• throw: Throws a user-defined exception.
  
  
• if…else: Executes a statement if a specified condition is true; otherwise, another statement can be executed.
  
  
• switch: Evaluates an expression, matches the expression’s value to a case clause, and executes statements associated with that case.
  
  
• try…catch: Marks a block of statements to try and specifies a response should an exception be thrown.
  
  
  

Loops

• do…while: Creates a loop that executes a specified statement until the test condition evaluates to false. The condition is evaluated after executing the statement, ensuring the
  statement executes at least once.
  
  
• for: Creates a loop with three optional expressions enclosed in parentheses, separated by semicolons, followed by a statement to be executed in the loop.
  
  
• for…in: Iterates over the enumerable properties of an object in arbitrary order, executing statements for each distinct property.
  
  
• for…of: Iterates over iterable objects (including arrays, array-like objects, iterators, and generators), invoking a custom iteration hook with statements to be executed for the
  value of each distinct property.
  
  
• for await…of: Iterates over async iterable objects, array-like objects, iterators, and generators, invoking a custom iteration hook with statements to be executed for the
  value of each distinct property.
  
  
• while: Creates a loop that executes a specified statement as long as the test condition evaluates to true. The condition is evaluated before executing the statement.