Custom search form with Javascript

Hi all,

I’m making a search form which requires some javascript. The form is located in a .php file but when i put the script there it doesn’t work and it gives me a blank page.

I need the following code. It works but not in the .php file. So what should I do?

<form target="frame2" id="searchform" name="searchform" onsubmit="javascript:if ((zoek.value == '') || zoek.value.match(/^ +$/)) return (false);" action="https://webshop.blz.nl/Webshop/SearchResults.aspx?" >

<input type="text" id="zoek" name="zoek" size="20" />
<input type="image" id="submit" name="submit" src="https://boekhandelwever.nl/wp-content/uploads/Schermafbeelding-2012-05-09-om-01.27.46.png" alt="Zoek & bestel!" /></center>

<input type="hidden" name="MemberNr" value="7211"/>
<input type="hidden" name="pf" value="eBook"/>
</form>

Thanks