AlertsBaseline · Widely available
The window.alert(), window.confirm(), and window.prompt() methods open modal dialogs for notifying the user, asking for confirmation, or entering text.
Supported in all major browsers for at least 30 months — safe to use without fallbacks. Baseline since Jul 29, 2015. Widely available since Jan 29, 2018.
Browser support
DesktopChrome
1+Supportedsince Dec 11, 2008
Current: 155Edge
12+Supportedsince Jul 29, 2015
Current: 154Firefox
1+Supportedsince Nov 9, 2004
Current: 157Safari
1+Supportedsince Jun 23, 2003
Current: 27MobileChrome Android
18+Supportedsince Jun 27, 2012
Current: 155Firefox Android
4+Supportedsince Mar 29, 2011
Current: 157Safari iOS
1+Supportedsince Jun 29, 2007
Current: 27How to use
This feature is Baseline widely available — use it freely, no fallback needed.
Example
Full syntax and examples are on MDN: alert.
Feature detection
JS · check before using
if ("Window" in globalThis && "alert" in Window.prototype) {
// Window.alert is available
}Specification
Sub-features
Support for each part of the feature (3). The overall table above shows when the whole feature works.
| Sub-feature | Chrome | Edge | Firefox | Safari | Chrome Android | Firefox Android | Safari iOS |
|---|---|---|---|---|---|---|---|
| Window.alert | 1 | 12 | 1 | 1 | 18 | 4 | 1 |
| Window.confirm | 1 | 12 | 1 | 1 | 18 | 4 | 1 |
| Window.prompt | 1 | 12 | 1 | 1 | 18 | 4 | 1 |