Javascript string is not an function

Question

I'm trying to add an onChange event on an select element. The html looks like this:

<select name="to" onChange="if(type(this.selectedIndex) != undefined){ alert('hello'); }">
    <option value="newsletter">Alle nieuwsbrief-abonnees</option>
    <option value="customer_all">Alle klanten</option>
    <option value="customer_group">Klantengroep</option>
    <option value="customer">Klanten</option>
    <option value="affiliate_all">Alle affiliates</option>
    <option value="affiliate">Affiliates</option>
    <option value="product">Producten</option>
    <option value="marketing">Alle Marketing Abbonnees</option>
    <option value="marketing_all">Alle Marketing</option>
    <option value="subscriber">Alle Nieuwsbrief Abbonnees &amp; Marketing Abbonnees</option>
    <option value="all">Alle Klanten &amp; Marketing</option>
    <option value="old_brian">Oude lijst Brian</option>
    <option value="old_dunamis">Oude lijst Dunamis</option>
    <option value="old_frohlich">Oude lijst Frohlich</option>
    <option value="old_gaithers">Oude lijst Gaithers</option>
    <option value="old_gospel7">Oude lijst Gospel7</option>
    <option value="old_lifeshop">Oude lijst Lifeshop</option>
    <option value="old_meyer">Oude lijst Meyer</option>
    <option value="old_opwekking">Oude lijst Opwekking</option>
    <option value="old_pelgrim_kerken">Oude lijst Perlgim Kerken</option>
    <option value="old_pelgrim_klanten">Oude lijst Pelgrim Klanten</option>
    <option value="old_pelgrim_pers">Oude lijst Pelgrim Pers</option>
    <option value="old_pelgrim_scholen">Oude lijst Pelgrim Scholen</option>
    <option value="old_test">Oude lijsten test</option>
</select>

Here's an JSFIDDLE of it

The onchange script came from an answer on stackoverflow: Is there an onSelect event or equivalent for HTML ?

But i get the following error:

Uncaught TypeError: string is not a function

I'm clueless, what's the problem? Can't you do an if statement in an onChange event? Or is it something else?

The comment on that answer is wrong about how to check the "selectedIndex" property. — Pointy
– Pointy, Commented Jul 29, 2013 at 16:50
I thought that already, but i'm not that good at js so i couldn't grasp the right way to do it :D — Mathlight
– Mathlight, Commented Jul 29, 2013 at 16:51

T.J. Crowder · Accepted Answer · 2013-07-29 16:43:45Z

6

type is not a built-in function. typeof is an operator, though, that may be what you wanted; it returns a string:

if (typeof this.selectedIndex !== "undefined") // But see below

But note that selectedIndex is never undefined on select elements. It may be -1, to indicate no selection, but not undefined. So:

if (this.selectedIndex !== -1)

Regarding the error: My guess is that you have a global variable called type, and that it contains a string. That would give you the error TypeError: string is not a function.

answered Jul 29, 2013 at 16:43

T.J. Crowder

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2 Comments

Mathlight Over a year ago

Thank you sir, that did it. the typeof was indeed the fix. Now using the second recomendation. Will accept when the time has come. Thanks again :D

K Z Over a year ago

@Mathlight Sorry for the confusion I've caused, and thanks for T.J Crowder for the correction!

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