Non-standard
This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

The mozbrowsershowmodalprompt event is fired when the content of a browser <iframe> calls the window.alert(), window.confirm(), or window.prompt() methods.

General info

Specification
Non standard
Interface
CustomEvent
Bubbles
Yes
Cancelable
Yes
Target
<iframe>
Default Action
None

Properties

Property Type Description
target Read only EventTarget The browser iframe
type Read only DOMString The type of event.
bubbles Read only Boolean Whether the event normally bubbles or not.
cancelable Read only Boolean Whether the event is cancellable or not.
details Read only Object A custom object.

details

The details property is an anonymous JavaScript object with the following properties:

promptType
A DOMString defining the type of the prompt. It can be alert, confirm, or prompt.
title
A DOMString representing the title of the prompt.
message
A DOMString representing the value passed to the window.alert(), window.confirm(), or window.prompt() methods within the browser <iframe>'s content.
returnValue
A DOMString representing the return value for the window.prompt() methods. This should be set by the embedder.
unblock()
A function to be called when the iframe is unblocked. Note that if the embedder calls preventDefault() on this event, the iframe is blocked until unblock() is called.

Obsolete properties of details

msg_name
A string representing the type of message. For that event, it's always showmodalprompt.
initialValue
A string representing the initial value for the window.prompt() methods.

Example

var browser = document.querySelector("iframe");

browser.addEventListener("mozbrowsershowmodalprompt", function( event ) {
  console.log("Asking for prompt:" + JSON.stringify(event.detail));
});

See also