JSON无法接受json_encode（）数组

Question

I am sending a simple array from my PHP file,

//example.php
if(0){
    return json_encode(['status'=>false, 'message'=>'Please enter a username']);
}

and in my ajax.js I have everything working, including the XHR object, and event handlers. All is find, except this line.

 // ...
 var x = JSON.parse(xmlhttp.responseText);
 console.log(x); 
// ...

But, I am getting the following error.

SyntaxError: JSON.parse: unexpected end of data at line 1 column 1 of the JSON data

I don't understand this. All the code is correct. Before using JSON, I used to pass from values from PHP using echo 'ok' and just do if(xmlhttp.responseText) == 'ok and it worked fine, but not with json

Answer 1

Two problems:

• you use return which does not print anything to the output wheras echo actually prints text. Try using:

• if(0) will always fail, so you will never print anything. You should use if(1) as trivial test. It is possible that you're PHP code can fail, but in that case you better also return an JSON formatted error message.

Something like:

if(test) { //test means you can do the action
    //do action
    echo json_encode(['return' => 'ok','result' => 'foobar']);
} else {
    echo json_encode(['return' => 'error']);
}