[Webkit-unassigned] [Bug 103936] New: Long pause/hang after deleting last character of password field on a large page

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=103936

           Summary: Long pause/hang after deleting last character of
                    password field on a large page
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: All
        OS/Version: All
            Status: UNCONFIRMED
          Severity: Normal
          Priority: P2
         Component: Forms
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: jmlai85 at gmail.com


Deleting the last remaining character in a password field causes a significant pause if the password field appears near the end of a large/complex page.

E.g. for a password field appearing at the bottom of a large document, type in "a" and then hit delete. There is a delay that is not present for password input forms appearing at the top of the page.

The pause/hang seems to be proportional (or worse) to the number of DOM elements *preceding* the password input field in the document tree. On a mobile device (tested on Mobile Safari on iOS), the hang can last for 10 seconds or longer for the slickdeals.net site mentioned below.

For a real-world example:

1) Go to http://slickdeals.net
2) Click on the "Log In" link in the upper right hand corner of the page.
3) A login form should appear. Type one or more characters into the password field.
4) Delete all characters from the password field. The last character takes slightly longer to remove.

For a synthetic example:

1) Download and open the attached html document.
2) Choose "Display 1000 items"
3) Enter and delete text in both password fields
4) Choose "Display 10000 items"
5) Enter and delete text in the password fields. This will hang the browser tab for an extended period of time.

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