This document summarizes JavaScript statements including: - Block statements which are delimited by curly brackets and can contain multiple statements with no block scope. - Conditional statements like if/else and switch statements which execute code conditionally. - Loop statements like for, do/while, while, and for/in which repeatedly execute code as long as conditions are met. - Exception handling statements like try/catch/finally and throw/catch which handle errors. - Function statements which declare reusable blocks of code and can return values. - Other statements like debugger, with, and empty statements.

2. JAVASCRIPT
STATEMENTS
Victor Perez

3. / BLOCK STATEMENT

4. BLOCK ⁄
STATEMENTS
● Delimited by a pair of curly brackets
● Contains one or more statements
● No block scope
○ added in ES6 via let keyword

5. / CONDITIONAL STATEMENTS

6. IF...⁄
STATEMENTS
ELSE ● Executes a statement if the condition is true
● Executes the optional second statement if the condition is false
● Both if and else can only have 1 statement

7. NESTED ⁄
STATEMENTS
IF...ELSE ● No elseif keyword

8. SWITCH ⁄
STATEMENTS
● Compares the expression agans all case expressions using strict equal
● Execution of the statements will start by the first matching case clause.
● break statement forces the program to break out of the switch
● default case expressions will always be executed

9. / LOOP STATEMENTS

10. FOR ⁄
STATEMENTS
● Executes a statement as long the condition is true
● Variable declaration in the initialization are in the
same scope as the for loop
● An empty condition always evaluates to true
● Only 1 statement

11. DO...⁄
STATEMENTS
WHILE ● Executes a statement at least once and is re-executing it each
time the condition evaluates to true
● Only 1 statement

12. WHILE ⁄
STATEMENTS
● Executes a statement as long as a specified condition evaluates to
true
● Only 1 statement

13. FOR...⁄
STATEMENTS
IN ● Iterates over the enumerable properties of an object
● On each iteration, a different property name is assigned to variable
● Arbitrary order
● Only 1 statement
● Don’t use it for array’s!

14. LABEL ⁄
STATEMENTS
● Label a statement
● The labeled statement can be used with break or continue
statements.
● Label can be any valid JavaScript identifier
● Avoid using labels!

15. BREAK ⁄
STATEMENTS
● Terminates the current loop, switch, or label statement
● Label is only optional if the break is used in a loop or switch, else its
required

16. CONTINUE ⁄
STATEMENTS
● Terminates execution of the statements in the current iteration of the
current loop
● Jumps to the final-expression of a for loop
● Jumps to the condition of a while loop

17. / EXCEPTION HANDLING STATEMENTS

18. THROW ⁄
STATEMENTS
● Throws a user-defined exception
● The statements after throw won't be executed
● Will execute the first catch block in the call stack
● Will terminate the program if there is not catch block in the full call
stack

19. TRY...⁄
STATEMENTS
CATCH ● Try block marks a block of statements to try
● Catch clause specifies a response, should an exception be thrown
● Finally clause executes after the try block and catch clause

20. / FUNCTION STATEMENTS

21. FUNCTION ⁄
STATEMENTS
● Declares function with the specified parameters
● You can use the function before you declared it
○ not by function expressions!

22. RETURN ⁄
STATEMENTS
● Ends function execution
● Specifies a value to be returned to the function caller
● Default value is undefined

23. / OTHER STATEMENTS

24. DEBUGGER ⁄
STATEMENTS
● Invokes any available debugging functionality
● This statement has no effect, if there is no debugger functionality available
● Execution is paused at the debugger statement

25. WITH ⁄
STATEMENTS
● Extends the scope chain for a statement
● Not recommended
● Forbidden in ECMAScript 5 strict mode.

26. EMPTY ⁄
STATEMENTS
● Is used to provide no statement, where the syntax requires one

27. / QUESTIONS?

28. THANKS
@VICTORAPEREZ
vpjs@victor-perez.nl