IntraWeb 15.3.x JavaScript code generation issue

[ebob42]

I may have found a bug, or at least an issue in IntraWeb 15.3.4 that breaks existing IntraWeb applications.

IntraWeb 15.3.x made a change in unit IWRenderContext.pas where procedure TIWPageContext40.AddToJavaScriptOnce(const ACode: string); contains the following code:

Code:

procedure TIWPageContext40.AddToJavaScriptOnce(const ACode: string);
var
  len: Integer;
  LCode: string;
begin
  len := Length(ACode);
  if len = 0 then begin
    Exit;
  end;
  if (len > 2) and (ACode[len-1] = CR) and (ACode[len] = LF) then begin
    LCode := ACode;
  end else begin
    LCode := ACode + EOL;
  end;
  if Pos(LCode, FJavaScript) <= 0 then begin
    FJavaScript := FJavaScript + LCode;
  end;
end;

The line with "if Pos(LCode, FJavaScript) <= 0 then begin" is introduced in IntraWeb 15.3.x (and was not present in IntraWeb 15.2.69).

This causes problems in our case where we have a page with a TIWControl and an onkeydown Script Event:

Code:

if (event.which == 13) {
  console.log("HW");
  IWBUTTON_LOGIN_onclick(event);
  return false;
} else {
  return true;
}

The problem is caused in unit IWRenderContext;

Code:

procedure TIWPageContext40.FinalizeContext;
begin
  ...

  AddToJavaScriptOnce('  return true;' + EOL + '}' + EOL); // last line
end;

The last call to AddToJavaScriptOnce tries to add a JavaScript snippet that only consists of "return true;" and the closing }.

However, inside the AddToJavaScriptOnce, this snippet is found to be already in the FJavaScript (because it's part of the onkeydown Script Event shown in the second screenshot).

As a consequence the last call to AddToJavaScriptOnce has no effect: the JavaScript is not added, and inside the browser we only get the "function Validate(){" without the closing "return true;" and }.

WORKAROUND

A simple workaround is to modify the

Code:

  AddToJavaScriptOnce('  return true;' + EOL + '}' + EOL);

And change it into

Code:

  AddToJavaScriptOnce('  return true;' + EOL + '} // Bob' + EOL);

However, any other place where we only add a "return true;" and "}" will still be ignored, so this may still break IntraWeb applications in other places

FIX?

I do not know the reason why the condition was added to the procedure TIWPageContext40.AddToJavaScriptOnce, but a real fix appears to be to remove that if statement (again, it was not present in IbtraWeb 15.2.69):

Code:

  if Pos(LCode, FJavaScript) <= 0 then begin // prevent LCode to be added to FJavaScript more than once?
    FJavaScript := FJavaScript + LCode;

Both the workaround and the fix seem to solve the problem for us. Please let me know your thoughts, especially why the new if-statement in the AddToJavaScriptOnce is required, so I can avoid any other issues that may be introduced by my workaround or fix.

Thanks in advance.

Groetjes, Bob Swart