Referencia de JavaScript 1.5:Sentencias

De MDC

This section describes all JavaScript statements. JavaScript statements consist of keywords used with the 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.

Syntax conventions: All keywords in syntax statements are non-italicized. Words in italics represent user-defined names or statements. Any portions enclosed in square brackets ("[" and "]") are optional. A comma-delimited sequence that includes an ellipsis ("...") indicates that the sequence is a list and all items in the sequence except the first are optional (e.g. only param1 is required in "param1, param2, ..., paramN").

block

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 labelled statement and transfers program control to the statement following the terminated statement.

const

Declares a global constant and initializes it to a value.

continue

Terminates execution of the statements in the current iteration of the current or labelled loop, and continues execution of the loop with the next iteration.

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, resulting in the specified statement executing at least once.

export

Allows a signed script to provide properties, functions, and object to other signed or unsigned scripts.

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.

for...in

Iterates a specified variable over all the properties of an object. For each distinct property, a specified statement is executed.

for each...in

Iterates a specified variable over all values of object's properties. For each distinct property, a specified statement is executed. The support for this statement was introduced in JavaScript 1.6 (Firefox 1.5).

function

Declares a function.

if...else

Executes a statement if a specified condition is true. If the condition is false, another statement can be executed.

import

Allows a script to import properties, functions, and objects from a signed script that has exported the information.

label

Provides an identifier that can be used with break or continue to indicate where the program should continue execution.

return

Specifies the value to be returned by a function.

switch

Evaluates an expression, matching the expression's value to a case label, and executes statements associated with that case.

throw

Throws a user-defined exception.

try...catch

Marks a block of statements to try, and specifies a response, should an exception be thrown.

var

Declares a variable, optionally initializing it to a value.

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.

with

Extends the scope chain for a statement.