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?

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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);