How to call javascript function in parent page from child page

Question

If I have Two pages like this :

• Parent.aspx
• Child.aspx

The parent page Contains a textbox(txt_grm) and a button ,when the user click the button i execute the following code :

            Session["grm"] = txt_grm.Text;
            string queryString = "Child.aspx";//Popup window
            string newWin = "window.open('" + queryString + "');";
            ClientScript.RegisterStartupScript(this.GetType(), "pop", newWin, true);

Now the Child page(popup) contains a link button with a specific text .

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How to call a javascript function in the parent page from the child page given the link button text as a parameter to this function then close the child page?

Say the link button in my child page :

<asp:LinkButton ID="lkSelect" runat="server" Font-Names="Tahoma" Font-Size="8" ><%# Eval("Cell_Data") %></asp:LinkButton>

I want to call the following javascript function in my parent page and close my child :

 function DrawPaths(room) {
            for (var i in engin.pois) {
                if (engin.pois[i].getName(engin.getLanguage()) == room) {
                    engin.showPath(engin.pois[i].getNode(), engin.pois[i]);
                    break;
                }
            }
            engin.showFloor(getFloor(), callback)
        }

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Note : room param is the link button text .