几个Postback时常用的javascript方法

有时候选择下拉框自动postback时，由于页面太长，postback后页面自动滚动到最上面，不能保持postback之前的位置，如果在Page_Load调用下面的方法就可以解决这个问题：

/**//// <summary> 
/// Persist ScrollBar's Position After a PostBack 
/// </summary> 
private void PersistScrollPosition() 
        { 
            System.Text.StringBuilder saveScrollPosition = new System.Text.StringBuilder(); 
            System.Text.StringBuilder setScrollPosition = new System.Text.StringBuilder(); 

            Page.RegisterHiddenField("__SCROLLPOS", "0"); 

            saveScrollPosition.Append("<script language='javascript'>"); 
            saveScrollPosition.Append("function saveScrollPosition() {"); 
            saveScrollPosition.Append(" document.forms[0].__SCROLLPOS.value = document.body.scrollTop;"); 
            saveScrollPosition.Append("}"); 
            saveScrollPosition.Append("document.body.onscroll=saveScrollPosition;"); 
            saveScrollPosition.Append("</script>"); 

            Page.RegisterStartupScript("saveScroll", saveScrollPosition.ToString()); 

            if (Page.IsPostBack) 
            { 
                setScrollPosition.Append("<script language='javascript'>"); 
                setScrollPosition.Append("function setScrollPosition() {"); 
                setScrollPosition.Append(" document.body.scrollTop = " + Request["__SCROLLPOS"] + ";"); 
                setScrollPosition.Append("}"); 
                setScrollPosition.Append("document.body.onload=setScrollPosition;"); 
                setScrollPosition.Append("</script>"); 

                Page.RegisterStartupScript("setScroll", setScrollPosition.ToString()); 
            } 
        }

跳到指定位置：

public void MoveTo(string name)
        {
            System.Text.StringBuilder sbScript = new System.Text.StringBuilder();

            sbScript.Append("<script language='JavaScript' type='text/javascript'>\n");
            sbScript.Append("<!--\n");
            sbScript.Append("document.location = '" + name + "';\n");
            sbScript.Append("// -->\n");
            sbScript.Append("</script>\n");

            Page.RegisterClientScriptBlock("MoveToNext", sbScript.ToString());
        }

 设置焦点到指定控件：

public static void SetFocus(System.Web.UI.Page Page,System.Web.UI.Control control)
        {
            StringBuilder sb = new StringBuilder();
    
            sb.Append("\r\n<script language='JavaScript'>\r\n");
            sb.Append("<!--\r\n"); 
            sb.Append("function SetFocus()\r\n"); 
            sb.Append("{\r\n"); 
            sb.Append("\tdocument.");
    
            System.Web.UI.Control p = control.Parent;
            while (!(p is System.Web.UI.HtmlControls.HtmlForm)) p = p.Parent; 
    
            sb.Append(p.ClientID);
            sb.Append("['"); 
            sb.Append(control.UniqueID); 
            sb.Append("'].focus();\r\n"); 
            sb.Append("}\r\n"); 
            sb.Append("window.onload = SetFocus;\r\n"); 
            sb.Append("// -->\r\n"); 
            sb.Append("</script>");
    
            control.Page.RegisterClientScriptBlock("SetFocus", sb.ToString());
        }