In yesterday’s post, I spoke of HTML5 Local Storage. Today, I would like to touch on HTML5 Session Storage. This will be a short post as session storage works a lot like local storage with one very large distinction…the persistence of the data.
With local storage, as you saw in my last post, the data survives to be accessed and utilized at a later browser session. Session storage is just the opposite. Any data that is stored in session storage “dies” after the browser session is complete. So how do we use Session Storage?
We will use the same code that we used for local storage…the HTML…
[code lang=”html”]
<!– HTML to demonstrate HTML5 Local Storage –>
<p>
<!– Button to click that will invoke our counter function. –>
<button onclick="clickCounter()" type="button">Click me!</button>
</p>
<!– Div that will hold the result of clicking the counter button. –>
<div id="result"></div>
<!– Instructions. –>
<p>Click the button to see the counter increase.</p>
<p>Close the browser tab (or window), and try again, and the counter will continue to count (is not reset).</p>
[/code]
Now for the JavaScript…
[code lang=”js”]
// Function demonstrate utilization of session storage
function clickCounter() {
// Test whether browser has HTML5 storage capability
if (typeof (Storage) !== "undefined") {
// Test to see if there is an HTML5 session storage variable key called clickcount
if (sessionStorage.clickcount) {
// Since the storage variable exists, let’s add one to the value and store it back in the session storage variable
// We are running the variable through the number function to ensure it is an integer
sessionStorage.clickcount = Number(sessionStorage.clickcount) + 1;
} else {
// The clickcount session storage variable does not exist, so we create it.
// This should only run the first time we run the program.
sessionStorage.clickcount = 1;
}
// Grab our result div and display the results pulled from session storage
document.getElementById("result").innerHTML = "You have clicked the button " + sessionStorage.clickcount + " time(s).";
} else {
// Display a message if the browser does not support HTML5 storage
document.getElementById("result").innerHTML = "Sorry, your browser does not support web storage…";
}
}
[/code]
Here is the beginning screen shot (it is the same as before)…
Here is a screen shot of the clicks in action…
So, again, the big difference is that the counter data would “die” after closing the browser.
Happy Coding!
Clay Hess
