IF-ELSE声明无效

Question

I'm trying my best to create a website. I need to create an IF-ELSE in ajax. It basically calls the content of an input called "greeting" and aims at writing "YES" if the user inserts a specific text and "NO" otherwise.

jQuery(document).ready(function () {
    var greeting = jQuery("#greeting").val();
    jQuery("#push-me").click(function () {
        jQuery.ajax({
            type: 'POST',
            url: 'http://www.boatsandbeats.com/wordpress/wp-admin/admin-ajax.php',
            data: {
                action: 'myAjax',
                greeting: jQuery("#greeting").val(),
            },
            success: function (data, textStatus, XMLHttpRequest) {
                if (data == "XYZ") == 0 {
                    jQuery("#test-div").html('');
                    jQuery("#test-div").append("YES");
                } else {
                    jQuery("#test-div").html('');
                    jQuery("#test-div").append("NOPE");
                }
            },
            error: function (MLHttpRequest, textStatus, errorThrown) {
                alert(errorThrown);
            }
        });
    });
});

While the rest of the code works just fine, it does not recognize the IF and takes everything as if it were true (therefore, printing "YES").

Can anybody be so kind and explain this to me?

Answer 1

it is not working because your if statement is wrong

 if (data == "XYZ") == 0 {

should be

 if (data.greeting == "XYZ") {

}

Answer 2

Step 1: check if your ajax actually returns something.

...//add the following line
 success: function (data, textStatus, XMLHttpRequest) {
    console.log(data);
    alert("Data logged." + data);
...

Step 2: what do you want to test? You want to know if data (the ajax return) is a string and that string is having the value "XYZ"?

 //change 
 if (data == "XYZ") == 0  
 //to
 if (data === "XYZ") 

Note the triple === it's not the same as == . The difference is that === will check if the variables have the same value and the same type.

In addition, in Javascrip can compare string similar to your style like using localeCompare() :

if (data.localeCompare("XYZ") === 0)

 /* strA.localeCompare(strB); Returns:   
 0:  exact match    
-1:  strA < strB    
 1:  strB > strA    
 */

UPDATE:

Assuming your php function is as the following:

function myAjax()
{
    $greeting = $_POST['greeting'];
    if (isset($_POST['greeting']))
        $greeting = $_POST['greeting']; 
    $results = "<h2>".$greeting."</h2>";
    die($results);
}

This is what's going to happen.

{
    //$greeting is being assigned a value from POST greetings, // in post is empty then $greeting will be empty as well. 
    $greeting = $_POST['greeting'];
    //You are validating POST greeting, although you already captured it's value and put it in $greeting, so why not using $greeting here instead?
    if (isset($_POST['greeting']))// this if has no {} so ONLY the first line after will be included in this IF condition. 
        $greeting = $_POST['greeting'];
    // this line will be exectue no matter what, so the value of $greeting will be entered into a string enclosed with <h2> tags. if POST greeting is empty, then $greeting will be empty of course. 
    $results  = "<h2>" . $greeting . "</h2>";
    //the variable $result now has "<h2></h2>" as it's value if $greeting is empty. 
    die($results); //echoing $result, or 
}

So, since you have confirmed that you are receiving "

" as a value for data variable returned from AJAX. Why are you comparing it to XYZ in your condition?

In your JS you are assigning "#greeting").val() to a variable greeting, then you use that variable as an array attribute for your ajax{data{greeting:jQuery("#greeting").val() }}

  var greeting = jQuery("#greeting").val();// what is the use of this line? 

Enclose your object attribute with "" eg "greeting".

  data: { "action": 'myAjax', "greeting": jQuery("#greeting").val(),// what is the value of "#greeting").val()? }, 

Answer 3

IF condition system is looks wrong,

if (data == "XYZ") == 0

You should use only, no need == 0

if (data == "XYZ"){
    //.... code here 
}

OR If ajax response in json

if (data.key == "XYZ"){
    //.... code here 
}

Answer 4

首先你需要检查数据是否会打印XYZ或打印[Object object]如果[Object object]那么你需要检查data.d ==“XYZ”

Answer 5

in success function first parse then compare like this

 var response=$.parseJSON(data);

 if(response.field=="XYZ")
 {
    jQuery("#test-div").html('');
    jQuery("#test-div").append("YES");
 }
 else
{
     jQuery("#test-div").html('');
    jQuery("#test-div").append("NOPE");
}