JavaScript statements

JAVASCRIPTSTATEMENTSVictor Perez

/ BLOCK STATEMENT

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● Delimited by a pair of curly brackets

● Contains one or more statements

● No block scope

○ added in ES6 via let keyword

BLOCKSTATEMENTS

/ CONDITIONAL STATEMENTS

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● 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

IF...ELSESTATEMENTS

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● No elseif keyword

NESTED IF...ELSESTATEMENTS

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● 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

SWITCHSTATEMENTS

/ LOOP STATEMENTS

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● 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

FORSTATEMENTS

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● Executes a statement at least once and is re-executing it each

time the condition evaluates to true


DO...WHILESTATEMENTS

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● Executes a statement as long as a specified condition evaluates to

true


WHILESTATEMENTS

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● Iterates over the enumerable properties of an object

● On each iteration, a different property name is assigned to variable

● Arbitrary order


● Don’t use it for array’s!

FOR...INSTATEMENTS

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● Label a statement

● The labeled statement can be used with break or continue

statements.

● Label can be any valid JavaScript identifier

● Avoid using labels!

LABELSTATEMENTS

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● 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

BREAKSTATEMENTS

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● 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

CONTINUESTATEMENTS

/ EXCEPTION HANDLING STATEMENTS

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● 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

THROWSTATEMENTS

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● 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

TRY...CATCHSTATEMENTS

/ FUNCTION STATEMENTS

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● Declares function with the specified parameters

● You can use the function before you declared it

○ not by function expressions!

FUNCTIONSTATEMENTS

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● Ends function execution

● Specifies a value to be returned to the function caller

● Default value is undefined

RETURNSTATEMENTS

/ OTHER STATEMENTS

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● Invokes any available debugging functionality

● This statement has no effect, if there is no debugger functionality available

● Execution is paused at the debugger statement

DEBUGGERSTATEMENTS

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● Extends the scope chain for a statement

● Not recommended

● Forbidden in ECMAScript 5 strict mode.

WITHSTATEMENTS

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● Is used to provide no statement, where the syntax requires one

EMPTYSTATEMENTS

/ QUESTIONS?

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JavaScript statements