Ajax POST Requests返回int而不是string

Question

I have the following JS code:

var dataString = "action=validateUsername"+
         "&username="+usernameRegi+
         "&lang="+lang;
$.ajax({
type: "POST",
url: "function.php",
data: dataString,
cache: false,
success: function(result)
    {           
        var expl=result.split("|");

                if(expl[0]=="1")
            alert("1");

                else if(expl[0]=="99")
        alert("99");
    }
});

This is my function.php

if($_POST["action"]=="validateUsername")
{
    $username=$_POST["username"];
    $lang=$_POST["lang"];

    $sqlSelect = "SELECT * FROM user where userName='".$username."'";
    $sqlQuery = mysql_query($sqlSelect);
    $rowCount = mysql_num_rows($sqlQuery);

    if($rowCount>0)
    {
    if($lang=="BM")
        echo "99|My msgA.";
    else
        echo "99|My msgB.";
    }
    else
    {
    if($lang=="BM")
        echo "1|My msgC.";
    else
        echo "1|My msgD.";  
    }
}

The problem is, my ajax request never alert 1 or 99 on success. And I found the problem is expl[0]==1 instead of expl[0]=="1".

When I turn my code to this one, it run smooth.:-

if(expl[0]==1)
alert("1");

else if(expl[0]==99)
alert("99");

This is happen only when I upload my code to the server. No problem on the localhost. What is the problem, is there any setting on the server that cause that problem?

Could anybody explain me, what is happening here?

Answer 1

It's because:

When you assign a numeric value to a variable, do not put quotes around the value. If you put quotes around a numeric value, it will be treated as text.