检查地址栏并使用javascript重定向

I would like to do the following:

Check address bar, if address is not something redirect to http://example.com else do nothing.

<script type='text/javascript'>
   if document.location != http://example.com
      window.location = 'http://example.com';
<script>

but it's not redirecting.

Please keep in min that the above code will be used in an echo tag in php.

EDIT:

I would also like be able to distinguish http://example.com/app/1?someparameters from http://example.com/app/2?someparameters

So if http://example.com/app/2?someparameters redirect to http://example.com/app/1

Already tried:

echo "<script type='text/javascript'>
    if(window.location.href.toLowerCase().indexOf("http://example.com/app2/..") != -1) {
        window.location.href = "http://example.com/apps/1/";
        alert("Done");
    }
    else
       alert("OK"); 
    </script>";

Try this

if(window.top.location.href.toLowerCase().indexOf('http://example.com/app/2') != -1)
   window.top.location.href = 'http://example.com/app/1';

This should work, but with a number of changes:

1) if condition must be in parens

2) why do you check document.location, but assign to window.location? You should actually assign to document.location.href

3) the string in condition must be in quotes, of course:

if (document.location.href !== 'http://myhost.com')
    document.location.href = 'http://myhost.com'