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JavaScript History Object Properties and Methods

Author : Exforsys Inc. Published on: 5th Aug 2007

JavaScript History Object Properties and Methods

In this JavaScript tutorial, you will learn about history object properties and methods, length, current, next, previous properties, back(), forward() and go() methods along with syntax and examples.

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The history property has the return value as history object, which is an array of history items having details of the URL's visited from within that window. Also, note that the History object is a JavaScript object and not an HTML DOM object.

General syntax of history property of Window Object:

window.history

The JavaScript runtime engine automatically creates this object.

An introduction on the history object and the properties and methods associated with it was covered in an earlier section. This section studies in detail the property and methods of the history object with an example for each.

Property of History Object:

length:

The length property of the history object returns the number of elements in the history list.

General syntax of length property of history Object:

history.length

An example to understand the length property of history object:

<html>
   <body>
      <script type="text/javascript">
          var ex = history.length;
          document.write("The number of pages visited
          before this page is" +ex+ " pages!!!.")

      </script>
   </body>
</html>

The output of the above program is

The number of pages visited before this page is 5 pages!!!

This means that there are 5 entries in the history list and denotes the number of pages visited before visiting the current page.

current:

This property contains the complete URL of the current History entry.

General syntax of current property of history Object:

history.current

The next property of history object contains the complete URL of the next element in the History list. This functionality or the URL visited is the same as pressing the forward button or menu.

General syntax of next property of history Object:

history.next

The previous property of history object contains the complete URL of the previous element in the History list. This functionality or the URL visited is the same as pressing the back button or menu.

General syntax of previous property of history Object:

history.previous

Methods of History Object:

back():

There may be scenarios where the programmer wishes to load the previous URL present in the history list. In this case, the programmer can make use of the back() method of the history object. The back() method of the history object takes the user to the previous page. The functionality results in the same as pressing the back button of the browser.

General syntax of back method of history Object:

history.back()

An example to understand the back method of history object:

<html>
   <head>
      <script type="text/javascript">
         function funback()
         {
              window.history.back()
         }

      </script>
   </head>

   <body>
       <input type="button" value="Press the Button to go
       to Previous Page!!!" onclick="funback()" />

   </body>
</html>

The output of the above program is a button with message as

Press the Button to go to Previous Page!!!

When this button is pressed, the control is navigated to the previous page.

forward():

The forward() method of the history object loads the next URL in the History list. The functionality results are the same as pressing the forward button of the browser.

General syntax of forward method of history Object:

history.forward()

An example to understand the forward method of history object in brief:

<html>
   <head>
      <script type="text/javascript">
         function funfor()
         {
              window.history.forward()
         }

      </script>
   </head>

   <body>
       <input type="button" value="Press the Button to go
       to Next Page!!!" onclick="funfor()" />

   </body>
</html>

The output of the above program is a button with message as

Press the Button to go to Next Page!!!

When this button is pressed, the control is navigated to next page (to the next URL) in the history list.

go():

If the programmer wishes to load a specified URL from the History list, then the go method of history object can be used.

General syntax of go method of history Object:

history.go(number)

history.go(URL)

The back method seen above is the same as history.go(-1) in terms of go method of history object. The forward method seen above is the same as history.go(1)

for example:

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<html>
   <head>
      <script type="text/javascript">
         function funfor()
         {
             window.history.go(1)
         }
      </script>
   </head>

   <body>
       <input type="button" value="Press the Button to go
       to Next Page!!!" onclick="funfor()" />
   </body>
</html>