Riferimento JavaScript

For an alphabetical listing see the sidebar on the left.

Control flow

Block (en-US)

A block statement is used to group zero or more statements. The block is delimited by a pair of curly brackets.

break

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

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

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.

Declarations

var

Declares a variable, optionally initializing it to a value.

let

Declares a block scope local variable, optionally initializing it to a value.

const (en-US)

Declares a read-only named constant.

Functions and classes

function (en-US)

Declares a function with the specified parameters.

function*

Generators functions enable writing iterators more easily.

return (en-US)

Specifies the value to be returned by a function.

class (en-US)

Declares a class.

Iterations

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 (en-US)

Creates a loop that consists of three optional expressions, enclosed in parentheses and separated by semicolons, followed by a statement executed in the loop.

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

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.

Others

debugger (en-US)

Invokes any available debugging functionality. If no debugging functionality is available, this statement has no effect.

export

Used to export functions to make them available for imports in external modules, another scripts.

import

Used to import functions exported from an external module, another script.

label (en-US)

Provides a statement with an identifier that you can refer to using a break or continue statement.

with (en-US)

Extends the scope chain for a statement.