String Comparison in JQuery Needs Explanation

Question

I'm having a trouble finding out an explanation with my code.. After echoing back a value from php and received by 'response' in jquery, I'm trying to compare a String from the value of response..

Not working:

success:function(response)
            {
                if (response=='added successfully')
                {
                   alert("");
                }
            },

I found a solution over the internet by putting up 'response' inside the $.trim()..And other solution i found out is to put 'exit();' after the echoing the value in PHP..

Working

success:function(response)
            {
                if ($.trim(response)=='added successfully')
                {
                   alert("");
                }
            },

AND

    if ($resultset)
    {
        echo 'added successfully';
        exit();
    }

Can anyone tell why the first code is not working (hoping for an easy way of explaining it)?

Answer 1

when you make ajax call say "echofile.php", in response it will give you empty leading and trailing space. in jsp it has one page directive to trim the output. <%@ page trimDirectiveWhitespaces="true" %> or you can trim response in your jquery success callback function.

To confirm my point you can put alert in your "not working" code. It would definitely have a leading or trailing space. so you have to trim it on either on client side or on the server side

Answer 2

Most likely you have some spaces after the ?> at the end of the script. PHP outputs everything outside of <?php ... ?> literally. The exit() causes the script to stop immediately, so it never gets to the end with the spaces.

Make sure that <?php is the very first line of the script. And you don't need ?> at the end of the script at all. If you don't need to go back into literal HTML mode, just end the script in PHP execution mode.