JavaScript Reference

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1. About this Reference
2. Global Objects
1. 2.1. Standard global objects (by category)
  1. 2.1.1. Constructors
  2. 2.1.2. Non-constructor functions
  3. 2.1.3. Other
2. 2.2. Standard global objects (alphabetically)
3. Functions and function scope
4. Statements
5. Operators
6. Comments
7. E4X (extension)
8. Appendix A - Reserved Words
9. Appendix B - Deprecated Features

Other objects in the global scope are either created by the user script or provided by the host application. The host objects available in Gecko-based browsers are documented in the Gecko DOM Reference.

For more information about the distinction between the DOM and core JavaScript, see The DOM and JavaScript article.

Functions and function scope

arguments

Statements

Statement	Description
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 label statement and transfers program control to the statement following the terminated statement.
`const`	Declares a read-only, named constant.
`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 objects to other signed or unsigned scripts. This feature is not in ECMA-262, Edition 3.
`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, in arbitrary order. For each distinct property, the 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.
`function`	Declares a function with the specified parameters.
`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 a statement with an identifier that you can refer to using a `break` or `continue` statement.
`let`	Declares a local variable, optionally initializing it to a value.
`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.