如何将数据从mysql数据库发送到JS脚本？

My intention is to query an MySQL database using a PHP script and then send the information to JavaScript.

I know how to encode the info into the JSON and send the request to the server script.

How does the PHP script know it has been queried it should answer?

Thank you for all the feedback provided!

Unfortunately, I was not sure, whether I had to use exit or header('Content-Type: application/json') as the answers suggested, I decided to use both.

In the end, I added both. This is what worked:

header('Content-Type: application/json');
echo json_encode($rows, JSON_NUMERIC_CHECK);
exit;

You need to send the header information specifying the content that you are returning. I have no idea how your application is setup but if you run this as a php script and define $data to be an array it would work fine.

header('Content-Type: application/json');
echo json_encode($data);

you should set content type in the http header to json

You can use json_encode

Let's say you want to have some JSON like:

{
  'name': 'bob',
  'weight': 150
}

In PHP, you could respond to the JS AJAX request with:

echo json_encode(array('name' => 'bob', 'weight' => 150));
exit;

Hope that helps!