Using Javascript can you get the value from a session attribute set by servlet in the HTML page

Question

No, you can’t. JavaScript is executed on the client side (browser), while the session data is stored on the server.

However, you can expose session variables for JavaScript in several ways:

a hidden input field storing the variable as its value and reading it through the DOM API
an HTML5 data attribute which you can read through the DOM
storing it as a cookie and accessing it through JavaScript
injecting it directly in the JS code, if you have it inline

In JSP you’d have something like:

<input type="hidden" name="pONumb" value="${sessionScope.pONumb} />

or:

<div id="product" data-prodnumber="${sessionScope.pONumb}" />

Then in JS:

// you can find a more efficient way to select the input you want
var inputs = document.getElementsByTagName("input"), len = inputs.length, i, pONumb;
for (i = 0; i < len; i++) {
    if (inputs[i].name == "pONumb") {
        pONumb = inputs[i].value;
        break;
    }
}

or:

var product = document.getElementById("product"), pONumb;
pONumb = product.getAttribute("data-prodnumber");

The inline example is the most straightforward, but if you then want to store your JavaScript code as an external resource (the recommended way) it won’t be feasible.

<script>
    var pONumb = ${sessionScope.pONumb};
    [...]
</script>

Leave a Comment Cancel reply