<script language="javascript">
    alert("Hell! UIWebView!");
</script>

- (void)login {
    NSString *requestText = [[NSString alloc] initWithFormat: @"%@?user=%@&password=%@", DEFAULT_URL, user.name, user.password];    // YES, I'm usin GET request to send password :)
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:requestText]];
    [webView loadRequest:request];
}

webView:runJavaScriptAlertPanelWithMessage:initiatedByFrame:

@interface UIWebView (JavaScriptAlert)

- (void)webView:(UIWebView *)sender runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(WebFrame *)frame;

@end

@implementation UIWebView (JavaScriptAlert)

- (void)webView:(UIWebView *)sender runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(WebFrame *)frame {
    UIAlertView* dialogue = [[UIAlertView alloc] initWithTitle:nil message:message delegate:nil cancelButtonTitle:@"Okay" otherButtonTitles:nil];
    [dialogue show];
    [dialogue autorelease];
}

@end