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Window: alert() method Baseline Widely available

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

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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.

In this article

• Syntax
• Examples
• Notes
• Specifications
• Browser compatibility
• See also

Syntax

jsalert() 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.

Return value

None (undefined).

Examples

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

Both produce:

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.

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).

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

Specifications

Specification
HTML# dom-alert-dev

Browser compatibility

See also

• <dialog> element
• confirm
• prompt

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This page was last modified on ⁨Oct 4, 2023⁩ by MDN contributors.

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1. Window
2. Instance properties
   1. caches
   2. closed
   3. cookieStore
   4. credentialless Experimental
   5. crossOriginIsolated
   6. crypto
   7. customElements
   8. devicePixelRatio
   9. document
   10. documentPictureInPicture Experimental
   11. event Deprecated
   12. external Deprecated
   13. fence Experimental
   14. frameElement
   15. frames
   16. fullScreen Non-standard
   17. history
   18. indexedDB
   19. innerHeight
   20. innerWidth
   21. isSecureContext
   22. launchQueue Experimental
   23. length
   24. localStorage
   25. location
   26. locationbar
   27. menubar
   28. mozInnerScreenX Non-standard
   29. mozInnerScreenY Non-standard
   30. name
   31. navigation
   32. navigator
   33. opener
   34. orientation Deprecated
   35. origin
   36. originAgentCluster
   37. outerHeight
   38. outerWidth
   39. parent
   40. performance
   41. personalbar
   42. scheduler
   43. screen
   44. screenLeft
   45. screenTop
   46. screenX
   47. screenY
   48. scrollbars
   49. scrollMaxX Non-standard
   50. scrollMaxY Non-standard
   51. scrollX
   52. scrollY
   53. self
   54. sessionStorage
   55. sharedStorage Deprecated
   56. speechSynthesis
   57. status Deprecated
   58. statusbar
   59. toolbar
   60. top
   61. trustedTypes
   62. viewport Experimental
   63. visualViewport
   64. window
3. Instance methods
   1. alert()
   2. atob()
   3. blur() Deprecated
   4. btoa()
   5. cancelAnimationFrame()
   6. cancelIdleCallback()
   7. captureEvents() Deprecated
   8. clearImmediate() Non-standard Deprecated
   9. clearInterval()
   10. clearTimeout()
   11. close()
   12. confirm()
   13. createImageBitmap()
   14. dump() Non-standard
   15. fetch()
   16. fetchLater() Experimental
   17. find() Non-standard
   18. focus()
   19. getComputedStyle()
   20. getDefaultComputedStyle() Non-standard
   21. getScreenDetails() Experimental
   22. getSelection()
   23. matchMedia()
   24. moveBy()
   25. moveTo()
   26. open()
   27. postMessage()
   28. print()
   29. prompt()
   30. queryLocalFonts() Experimental
   31. queueMicrotask()
   32. releaseEvents() Deprecated
   33. reportError()
   34. requestAnimationFrame()
   35. requestFileSystem() Non-standard Deprecated
   36. requestIdleCallback()
   37. resizeBy()
   38. resizeTo()
   39. scroll()
   40. scrollBy()
   41. scrollByLines() Non-standard
   42. scrollByPages() Non-standard
   43. scrollTo()
   44. setImmediate() Non-standard Deprecated
   45. setInterval()
   46. setResizable() Non-standard Deprecated
   47. setTimeout()
   48. showDirectoryPicker() Experimental
   49. showOpenFilePicker() Experimental
   50. showSaveFilePicker() Experimental
   51. sizeToContent() Non-standard
   52. stop()
   53. structuredClone()
   54. webkitConvertPointFromNodeToPage() Non-standard Deprecated
   55. webkitConvertPointFromPageToNode() Non-standard Deprecated
4. Events
   1. afterprint
   2. appinstalled
   3. beforeinstallprompt
   4. beforeprint
   5. beforeunload
   6. blur
   7. devicemotion
   8. deviceorientation
   9. deviceorientationabsolute
   10. error
   11. focus
   12. gamepadconnected
   13. gamepaddisconnected
   14. hashchange
   15. languagechange
   16. load
   17. message
   18. messageerror
   19. offline
   20. online
   21. orientationchange Deprecated
   22. pagehide
   23. pagereveal
   24. pageshow
   25. pageswap
   26. popstate
   27. rejectionhandled
   28. resize
   29. scrollsnapchange Experimental
   30. scrollsnapchanging Experimental
   31. storage
   32. unhandledrejection
   33. unload
   34. vrdisplayactivate Non-standard Deprecated
   35. vrdisplayconnect Non-standard Deprecated
   36. vrdisplaydeactivate Non-standard Deprecated
   37. vrdisplaydisconnect Non-standard Deprecated
   38. vrdisplaypresentchange Non-standard Deprecated
5. Inheritance
   1. EventTarget