if statement in onclick event

[matthewst]

It always says "nothing in text box"

<input type="text" class="formSmallTextbox" name="a_number" size="4" value="<?="$a_number"?>">

<input type="submit" name="submit" class="formTextbox" value="Submit" onClick="<?php
    if ($a_number >= '1'){
    echo "return confirm('something in text box')\">";}                else{
    echo "return confirm('nothing in text box')\">";}
    ?>