Window.alert()

The Window.alert() method displays an alert dialog with the optional specified content and an OK button.

Syntax

window.alert(message);

Parameters

message Optional
A string you want to display in the alert dialog, or, alternatively, an object that is converted into a string and displayed.

Example

window.alert("Hello world!");
alert("Hello world!");

Both produce:

Image:AlertHelloWorld.png

Notes

The alert dialog should be used for messages which do not require any response on the part of the user, other than the acknowledgement of the message.

The following text is shared between this article, DOM:window.prompt and DOM:window.confirm Dialog boxes are modal windows - they prevent the user from accessing the rest of the program's interface until the dialog box is closed. For this reason, you should not overuse any function that creates a dialog box (or modal window).

Specification

Specification Status Comment
HTML Living Standard
The definition of 'alert()' in that specification.
Living Standard

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
alertChrome Full support 1
Notes
Full support 1
Notes
Notes Starting with Chrome 46, this method is blocked inside an <iframe> unless its sandbox attribute has the value allow-modals.
Edge Full support 12Firefox Full support 1IE Full support 4Opera Full support 3
Notes
Full support 3
Notes
Notes Starting with Opera 33, this method is blocked inside an <iframe> unless its sandbox attribute has the value allow-modals.
Safari Full support 1WebView Android Full support 1
Notes
Full support 1
Notes
Notes Starting with WebView 46, this method is blocked inside an <iframe> unless its sandbox attribute has the value allow-modals.
Chrome Android Full support 18
Notes
Full support 18
Notes
Notes Starting with Chrome 46, this method is blocked inside an <iframe> unless its sandbox attribute has the value allow-modals.
Firefox Android Full support 4Opera Android Full support 10.1
Notes
Full support 10.1
Notes
Notes Starting with Opera 33, this method is blocked inside an <iframe> unless its sandbox attribute has the value allow-modals.
Safari iOS Full support 1Samsung Internet Android Full support 1.0
Notes
Full support 1.0
Notes
Notes Starting with Samsung Internet 5.0, this method is blocked inside an <iframe> unless its sandbox attribute has the value allow-modals.

Legend

Full support  
Full support
See implementation notes.
See implementation notes.

See also