HTML5 Web Storage
HTML5 web storage, a better local storage than cookies.
What is HTML5 Web Storage?
With HTML5, web pages can store data locally within the user's browser.
Earlier, this was done with cookies. However, Web Storage is more secure and
faster. The data is not included with every server request, but used ONLY when
asked for. It is also possible to store large amounts of data, without affecting
the website's performance.
The data is stored in key/value pairs, and a
web page can only access data stored by itself.
Browser Support
Web storage is supported in Internet Explorer 8+, Firefox, Opera, Chrome, and
Safari.
Note: Internet Explorer 7 and earlier versions, do not support web
storage.
localStorage and sessionStorage
There are two new objects for storing data on the client:
- localStorage - stores data with no expiration date
- sessionStorage - stores data for one session
Before using web storage, check browser support for localStorage and
sessionStorage:
if(typeof(Storage)!=="undefined")
{
// Yes!
localStorage and sessionStorage support!
// Some code.....
}
else
{
// Sorry! No web
storage support..
}
The local Storage Object
The local Storage object stores the data with no expiration date. The data
will not be deleted when the browser is closed, and will be available the next
day, week, or year.
Example
localStorage.lastname="Smith";
document.getElementById("result").innerHTML="Last
name: "
+ localStorage.lastname;
Try it yourself »
Example explained:
- Create a localStorage key/value pair with key="lastname" and value="Smith"
- Retrieve the value of the "lastname" key and insert it into the element
with id="result"
Tip: Key/value pairs are always stored as strings. Remember
to convert them to another format when needed.
The following example counts the number of times a user has clicked a button.
In this code the value string is converted to a number to be able to increase
the counter:
Example
if (localStorage.clickcount)
{
localStorage.clickcount=Number(localStorage.clickcount)+1;
}
else
{
localStorage.clickcount=1;
}
document.getElementById("result").innerHTML="You have clicked the button " +
localStorage.clickcount + " time(s).";
Try it yourself »
The sessionStorage Object
The sessionStorage object is equal to the localStorage object,
except
that it stores the data for only one session. The data is
deleted when the user closes the browser window.
The following example counts the number of times a user has clicked a button, in the current session:
Example
if (sessionStorage.clickcount)
{
sessionStorage.clickcount=Number(sessionStorage.clickcount)+1;
}
else
{
sessionStorage.clickcount=1;
}
document.getElementById("result").innerHTML="You have clicked the button " +
sessionStorage.clickcount + " time(s) in this session.";
Try it yourself »
Refferenced from W3school »