Declarações e instruções

JavaScript applications consist of statements with an appropriate syntax. A single statement may span multiple lines. Multiple statements may occur on a single line if each statement is separated by a semicolon. This isn't a keyword, but a group of keywords.

Declarações e instruções por categoria

For an alphabetical listing see the sidebar on the left.

Controlo de Fluxo

Block
A block statement is used to group zero or more statements. The block is delimited by a pair of curly brackets.
break (en-US)
Terminates the current loop, switch, or label statement and transfers program control to the statement following the terminated statement.
continue (en-US)
Terminates execution of the statements in the current iteration of the current or labeled loop, and continues execution of the loop with the next iteration.
Empty (en-US)
An empty statement is used to provide no statement, although the JavaScript syntax would expect one.
if...else (en-US)
Executes a statement if a specified condition is true. If the condition is false, another statement can be executed.
switch (en-US)
Evaluates an expression, matching the expression's value to a case clause, and executes statements associated with that case.
throw
Throws a user-defined exception.
try...catch (en-US)
Marks a block of statements to try, and specifies a response, should an exception be thrown.

Declarações

var (en-US)
Declares a variable, optionally initializing it to a value.
let (en-US)
Declares a block scope local variable, optionally initializing it to a value.
const (en-US)
Declares a read-only named constant.

Funções e classes

function (en-US)
Declara as funções com parâmetros especificados.
function* (en-US)
Generators functions enable writing iterators more easily.
async function (en-US)
Declares an async function with the specified parameters.
return
Specifies the value to be returned by a function.
class (en-US)
Declara uma Classe.

Iterações

do...while (en-US)
Creates a loop that executes a specified statement until the test condition evaluates to false. The condition is evaluated after executing the statement, resulting in the specified statement executing at least once.
for
Creates a loop that consists of three optional expressions, enclosed in parentheses and separated by semicolons, followed by a statement executed in the loop.
This deprecated API should no longer be used, but will probably still work. This API has not been standardized. for each...in
Iterates a specified variable over all values of object's properties. For each distinct property, a specified statement is executed.
for...in (en-US)
Iterates over the enumerable properties of an object, in arbitrary order. For each distinct property, statements can be executed.
for...of (en-US)
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.
while (en-US)
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.

Outros

debugger (en-US)
Invokes any available debugging functionality. If no debugging functionality is available, this statement has no effect.
export (en-US)
Used to export functions to make them available for imports in external modules, another scripts.
import (en-US)
Used to import functions exported from an external module, another script.
import.meta
A meta-property exposing context-specific metadata to a JavaScript module.
label (en-US)
Provides a statement with an identifier that you can refer to using a break or continue statement.
This deprecated API should no longer be used, but will probably still work. with (en-US)
Extends the scope chain for a statement.

Especificações

Especificação Estado Comentário
ECMAScript 1st Edition (ECMA-262)
The definition of 'Statements' in that specification.
Standard Initial definition
ECMAScript 3rd Edition (ECMA-262)
The definition of 'Statements' in that specification.
Standard  
ECMAScript 5.1 (ECMA-262)
The definition of 'Statements' in that specification.
Standard  
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'ECMAScript Language: Statements and Declarations' in that specification.
Standard New: function*, let, for...of, yield, class
ECMAScript (ECMA-262)
The definition of 'ECMAScript Language: Statements and Declarations' in that specification.
Living Standard  

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Consultar também