Bug 74961 – window.prompt() returns empty string instead of null when Cancel is pressed

• Component: WebCore Misc.
• Status: NEW

[Paul Wieland]

JavaScript window.prompt() should return null when the user clicks the cancel button. Instead an empty string is returned. This seems to be a newly introduced bug with Safari version 5.1.

Sample:

console.log(null != window.prompt('this is a test'));


Pressing escape / clicking cancel should log false. Hitting enter / clicking OK should log true. Instead, window.prompt() returns true no matter which button is pressed.

[Daniel Bates]

From briefly debugging, m_client.runJavaScriptPrompt() (*) in WebUIClient::runJavaScriptPrompt() returns the empty string when the Cancel button is pressed in the NSAlert dialog. Concatenating the multi-process call chains into one chain, the call chain leading up to WebUIClient::runJavaScriptPrompt() has the form: 

... => DOMWindow::prompt() => Chrome::runJavaScriptPrompt() => WebChromeClient::runJavaScriptPrompt() => ... => WebUIClient::runJavaScriptPrompt()

Ultimately WebUIClient::runJavaScriptPrompt() returns the empty string through this chain (in reverse order) to JavaScript. Therefore we return the empty string when the Cancel button is pressed in the JavaScript prompt() dialog.

(*) <http://trac.webkit.org/browser/trunk/Source/WebKit2/UIProcess/WebUIClient.cpp?rev=102935#L142>

For completeness, this bug doesn't occur in single-process mode in Mac Safari Version 5.1.2 (7534.52.7). That is, window.prompt() returns null when the Cancel button is pressed in the JavaScript prompt() dialog.

[Alexey Proskuryakov]

<rdar://problem/10677480>