javascript - HTML make <option> invalid -


i have following piece of code in contact form site designing:

<select id="category" name="category">     <option value="0" selected="selected" disabled>category</option>     <option value="1">general info</option>     <option value="2">booking</option>     <option value="3">auditions</option> </select>

i set menu such user cannot leave category selected option. there way html? if not, how javascript?

thank you

when user click on option, can´t return first 1 back. can submit form without change, need validate via js.

it's quite simple, 

function validate() {     var select = document.getelementbyid('category');     return !select.value == 0; }

and form in html:

<form onsubmit="return validate()">...</form>

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