post a form inside a javascript

WinHandle=window.open('',winName,features);
var form1 = WinHandle.document.createElement("form");
And I have something like this 
WinHandle.form1.setAttribute("id",id);
WinHandle.form1.setAttribute("method","post");
WinHandle.form1.setAttribute("action",target);

When I execute thi开发者_开发技巧s code I m geting the below script error:

Winhandle.form1 is null. 

can any one please help me?

When you created the form, you assigned the reference to the variable form1. So, to access that reference, continue to use the variable as declared:

form1.setAttribute("id",id);
form1.setAttribute("method","post");
form1.setAttribute("action",target);