Question

I’m using the following function but it does work, can someone please point out what is wrong.

The vb variable is generated from a database query.

window.onload function PostCodeChecker() {
if (<%= sPostalCode %> !== 'SW') {
alert("This is not an SW Postal Code");
}
}

Answer 1

What’s really happening here is that your server-side code is swapping in the value where you’ve put <%= sPostalCode %>, and sending the result to the browser. So if the sPostalCode were (say) “NW10”, you’d get

window.onload function PostCodeChecker() {
if (NW10 !== 'SW') {
//  ^--- ERROR (unless you happen to have a client-side variable by that name, which I'm guessing you don't)
alert("This is not an SW Postal Code");
}
}

So you’ll need quotes around it (and you’ll need to add the missing =), like this:

//            v-- was missing
window.onload = function PostCodeChecker() {
if ('<%= sPostalCode %>' !== 'SW') {
//  ^--- here          ^--- and here
alert("This is not an SW Postal Code");
}
}

…so that what goes to the browser is:

window.onload = function PostCodeChecker() {
if ('NW10' !== 'SW') {
alert("This is not an SW Postal Code");
}
}

That assumes that the string won’t have any ' characters in it, or other characters that would result (when the server-side processing is done and the result sent to the browser) in an invalid JavaScript string literal.

Of course, you could just do this:

<% If sPostalCode <> "SW" Then %>
window.onload = function() {
alert("This is not an SW Postal Code");
}
<% End If %>

…since it’s a server-side variable, you can do the test server-side.

---

Side note: This form of expression:

something = function name() { ... };

…has issues on various browsers, most notably IE. It’s called a named function expression because it’s a function expression where the function has a name (name, in this case). On IE it results in two completely separate functions being created, which can be ever so confusing. More: Double-take