使用JSON，将变量从php传递到javascript

Question

I wonder why is it not working?

check_login.php

<?php
session_start();
$data = array("username" => "true");
echo json_encode($data);
?>

my js file var linkName;

$.ajax({
    type: "POST",
    url: "check_login.php",
    dataType: "json",
    success: function(json){
    if(json.username != "true")
    {
      //do something
    }
    }
});

I am trying to get the username after checking whether or not the user has signed in yet in the php file, something like passing a session variable. But currently passing a string seems to already have a problem. Any know what I did wrong here?

Still not working the code above. Anyone want to help me out here?

Answer 1

You have an error in your PHP code. The square bracket ] is not needed in line 3. And, of course you should use echo json_encode($data);

Answer 2

    `if(json.data.username != "true")` is wrong you do not have data object

    `if(json.username != "true")` try this

Answer 3

You should echo the json data so that the page you get using ajax contains the string data.

<?php
session_start();
$data = array("username" => "true");
echo(json_encode($data));
?>

$.ajax({
    type: "POST",
    url: "check_login.php",
    dataType: "json",
    success: function(json){
       console.log(json)
    }
});

Also some times you might need to set the content type of the header in php to json.

Answer 4

try to send the header

header("Content-Type: application/json", true);
print json_encode($data);

Answer 5

 return json_encode($data);

我认为您必须返回数据，而不仅仅是json编码！