javascript display different error message
<p>I have two page (page1.php and page2.php) that need to put the javascript coding.
On the page1.php, there have two images link to page2.php.</p>

<p>This is the code for page1.php:</p>

<pre><code>&lt;a href="page2.php"&gt;&lt;img src="btn1.png" id="img1"&gt;&lt;/a&gt;
&lt;a href="page2.php"&gt;&lt;img src="btn2.png" id="img2"&gt;&lt;/a&gt;
</code></pre>

<p>This is code for page2.php:</p>

<pre><code>&lt;input id="t_c" type="checkbox" name="t_c" value="1"/&gt;
&lt;input type="image" value="continue" src="images/btn_cont.png"/&gt;
</code></pre>

<p>If user click image1, it will go to page2.php. then if user didn't click the checkbox, there will display the error message.</p>

<p>If user click image2, it will go to page2.php. then if user didn't click the checkbox, there will display different error message.</p>
