Partial Page Rendering Using Hidden IFrame

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Published: 23rd May 2007
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Partial Page Rendering Using Hidden IFrame

Executive Summary:

Partial-page rendering removes the need for the whole web page to be

refreshed as the result of a postback. Instead, only individual regions

of the page that have changed are updated. As a result, users do not

see the whole page reload with every postback, which makes user

interaction with the Web page more seamless.

Developers that want to add such behaviors to their web pages are often

faced with a difficult decision. All of these actions can be

implemented using a very simple solution: by refreshing the entire page

in response to the user interaction. However this solution is easy but

not always desirable. The full page refresh can be slow, giving the

user the impression that the application is unresponsive. Another

option is to implement such actions using JavaScript (or other

client-side scripting technologies). This results in faster response

times, at the expense of more complex, less portable code. JavaScript

may be a good choice for simple actions, such as updating an image.

However, for more complicated actions, such as scrolling through data

in a table, writing custom JavaScript code can be a very challenging


This paper provides a solution which avoids the drawbacks of the full

page refresh and custom JavaScript solutions. In this paper partial

page rendering functionality provides the ability to re-render a

limited portion of a page. As in the full page render solution, partial

page rendering sends a request back to the application on the

middle-tier to fetch the new contents. However, when partial page

rendering is used to update the page, only the modified contents are

sent back to the browser. This paper gives the solution using a hidden

IFrame and simple JavaScript to merge the new contents back into the

web page. The end result is that the page is updated without custom

JavaScript code, and without the loss of context that typically occurs

with a full page refresh.


Web pages typically support a variety of actions, such as entering and

submitting form data and navigating to different pages. Many web pages

also support another type of action, which is to allow the user to make

modifications to the contents of the web page itself without actually

navigating to a different page. Some examples of such actions include.

Clicking on a link could update an image on the same page. For example,

an automobile configuration application might update an image of a car

as the user chooses different options, such as the preferred color.

Selecting an item from a choice box might result in modifications to

other fields on the same page. For example, selecting a car make might

update the set of available car models that are displayed.

Clicking a link or selecting an item from a choice could be used to

scroll to a new page of data in a table. Clicking a button in a table

might add a new row to the table.

All of these actions are similar in that they result in the same page

being re-rendered in a slightly different state. Ideally, these changes

should be implemented as seemlessly as possible, so that the user does

not experience a loss of context which could distract from the task at


Partial page rendering can be implemented with very simple solution

using a hidden IFrame and minimal JavaScript. Any part of the page can

be partially rendered with using a div or table tags in HTML.

Page Elements That May Change During PPR:

•Re-Render Data: The same fields are redrawn but their data is updated.

Examples include the Refresh Data action button, or recalculate totals

in a table.

•Re-render Dependent Fields: Fields may be added, removed, or change

sequence, and data may be updated. Examples include the Country choice

list, which may display different address fields, and toggling between

Simple and Advanced Search.

•Hide/Show Content: Both fields and data toggle in and out of view.

Page Elements That Do Not Change During PPR:

Some page elements are always associated with a page, regardless of the

content displayed on the page.

As a general rule of thumb, elements above the page title (except

message boxes) remain constant and do not change position, whereas

elements in footer constant but may move up or down the page to

accommodate changes to page content. The following elements never

change when PPR is initiated:

• Branding

• Global buttons

• Tabs, Horizontal Navigation, SubTabs

• Locator elements: Breadcrumbs, Train, Next/Back Locator

• Quick links

• Page titles (first level header)

• Page footer

• Separator lines between the Tabs and Page Title

In most cases the following elements will also not change, other than

moving up or down the page to accommodate changed elements.

Nevertheless, in certain cases actions on the page may require them to

be redrawn:

• Side Navigation, unless it contains a Hide/Show control.

• Subtabs

• Contextual information

• Page-level action/navigation buttons

• Page-level Instruction text

• Page-level Page stamps

• Page-level Key Notation

In all above scenarios this solution can be used to achieve the good

performance and user interaction of the web pages.

Contexts in Which PPR Should Not Be Used:

When PPR is implemented correctly, it significantly improves

application performance. When performance improvement is not possible

with PPR, it should not be implemented, thus avoiding unnecessary code

bloat, PPR can't be used when navigating to another page (with a

different title).

Partial Page Rendering Solution:

Solution provided to the Partial Page Rendering using simple hidden

iframe and JavaScript, this can be used as a generalized solution to

all the Partial Page Rendering scenarios.

Below is the main html (Table 1.1), which will have two buttons one is

to show a simple table which will be generated by the server, and

another button to remove the table.



[title] Main Document [/title]

[script language="JavaScript"]


function showTable() {



function removeTable() {







[iframe id="hiframe"








[td colspan="2"][div id="tableId"][/div][/td]



[td][input type="button" value="Show Table"


[td][input type="button" value="Remove Table"






Table 1.1

[iframe id="hiframe" style="visibility:hidden;display:none"][/iframe]

This iframe tag is used as target to the Partial Page Rendering


The tag [input type="button" value="Show Table" onclick="showTable()"]

gives the user action to get the contents of a table from the server,

in this solution sample html is provided to render the table, which

supposed to be generated by the server.

The tag [input type="button" value="Remove Table"

onclick="removeTable()"] gives the user to remove the table from the

user interface.

The JavaScript

function showTable() {



Is used to get the contents from the server, the line

hiframe.location="./table.htm"; sends the GET request to the server,

and as a response iframe gets the HTML.

If the requirement insists to send a POST request for Partial Page

rendering Response, that can be achieved by setting the html form

element target attribute as the name of hidden iframe.

The code for the post request looks like

[form method="post" action="/myaction" target="hiframe"]

Partial Page Rendering Server Response:

Table 1.2 shows the sample response from the server for Partial Page

Rendering. This response has the JavaScript code to transfer the HTML

from hidden iframe to main page.



[script language="JavaScript"]


function iframeLoad() {

parent.document.getElementById("tableId").innerHTML =






[body onload="iframeLoad()"]

[div id="tableId"]














Table 1.2

The tag [div id="tableId"] encloses the content to transfer from hidden

iframe to main page.











This is the content to show the table to user.

The code [body onload="iframeLoad()"] is used for triggering the action

to transfer the content.

function iframeLoad() {

parent.document.getElementById("tableId").innerHTML =



This JavaScript function does the transferring data from the hidden

iframe to main page.

parent.document.getElementById("tableId").innerHTML This part refers to

tag div html id in main page and this part

document.getElementById("tableId").innerHTML refers the HTML of the

Partial Page Response.


Improve the user experience with Web pages that are richer, that are

more responsive to user actions, and that behave like traditional

client applications. Reduce full-page refreshes and avoid page flicker.

Partial page rendering using iframe is a very simple solution.








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