Window: alert() method

BaselineWidely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

window.alert() instructs the browser to display a dialog with an optional message, and to wait until the user dismisses the dialog.

Under some conditions — for example, when the user switches tabs — the browser may not actually display a dialog, or may not wait for the user to dismiss the dialog.

Syntax

alert()alert(message)

Parameters

messageOptional: A string you want to display in the alert dialog, or, alternatively, an object thatis converted into a string and displayed.

Black alert dialog box. At the top left small circle icon follow by white open and close square brackets containing this white text: JavaScript application. Below on the left, a Hello world! white text. And on the bottom right a small blue button. The button's text is: ok in black.

Notes

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

Dialog boxes are modal windows - theyprevent the user from accessing the rest of the program's interface until the dialog boxis closed. For this reason, you should not overuse any function that creates a dialogbox (or modal window).

Alternatively<dialog> element can be used to display alerts.