PHP向ajax结果添加不需要的换行符

Question

Why is PHP adding a line break to my simple AJAX result? This couldn't be much easier. Am I missing something?

Here is my JS:

$(document).ready(function() {
    $('#inputEmail').change(function(){
        // Check to see if email exists
        var email = $('#inputEmail').val();
        //alert(email);
        $.ajax({
            url : "php/checkUserEmail.php",
            type: "POST",
            dataType: "text",
            data: {email: email},                
            success: function(data){
                alert(data);
                if(data === "exists"){
                    alert(data);                        
                }                    
            },
            error: function (jqXHR, textStatus, errorThrown)
            {
                alert("ajax error");
            }
        });              
    });
});

Here is my php:

<?php 

include_once("db_connect.php");

// Catch results sent via $.post and assigns them to php variables.
$email = $_POST['email'];

// Check to see if email exists
$sql = "SELECT * FROM users WHERE email = '$email'";
$conn->prepare($sql);
$result = $conn->query($sql);
$rowCnt = $result->num_rows;

if($rowCnt == 0){
    echo trim('new');
}else{
    echo trim('exists');
}

For whatever reason, my result data string is returned as /r/nexists, rather than just exists, and thus never gets into my if block, even if I only use == to evaluate the condition. I tried adding the trim() function as you can see without result. Your help is much appreciated as this has taken me hours of time for a stupid if condition.

Answer 1

Check if there is an "empty" space after or before the php question marks, those line-breaks are also represented as part of the response.

I mean here
<?php?>
And here

Answer 2

I found a solution but I still do not like or understand what is happening. You should be able to return a simple string for a result. Anyway, what I did was to just echo the number of rows returned from the DB to my ajax success function. I then checked if the result was > 0 on the client and am finally in my IF block. Here is what I did:

JS:

$(document).ready(function() {
    $('#inputEmail').change(function(){
        // Check to see if email exists
        var email = $('#inputEmail').val();
        //alert(email);
        $.ajax({
            url : "php/checkUserEmail.php",
            type: "POST",
            dataType: "text",
            data: {email: email},                
            success: function(data){                    
                console.log(data);
                if(data > 0){
                    console.log("HURRAY!  I'm in my IF");   
                }                    
            },
            error: function (jqXHR, textStatus, errorThrown)
            {
                alert("ajax error");
            }
        });              
    });
});

Here is the PHP:

    // Catch results sent via $.post and assigns them to php variables.
    $email = $_POST['email'];

    // Check to see if email exists
    $sql = "SELECT * FROM users WHERE email = '$email'";
    $conn->prepare($sql);
    $result = $conn->query($sql);
    $rowCnt = $result->num_rows;

    echo $rowCnt;
?>

This works, and is actually maybe alittle more elegant, but you should be able to return a string without issue.

John