CORS policy: No 'Access-Control-Allow-Origin'

This is the error that appears in the browser console when you click on "Subscribe" in the newsletter widget.

Access to XMLHttpRequest at 'http://manage.kmail-lists.com/ajax/subscriptions/subscribe' from origin 'http://demo2. has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

Hello I have added below code

<script>
var settings = {
  "url": "https://a.klaviyo.com/api/v2/list/YwvFLh/members?api_key=pk_xxxxxxxxxxxxxxxxxxxxxxxxxxxxemails=xxxxxxxxxx@gmail.com",
  "method": "GET",
  "timeout": 0,
  "headers": {
    "Authorization": "Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJhdWQiOm51bGwsImlzcyI6InJlVHVHdS1BVHhlaDZ0OVpGaUgxQ2ciLCJleHAiOjE2NzI0NzE3NDAsImlhdCI6MTU5OTk3ODc2NH0.Ct4MZ_r0Uy4bE3EvutB22YZHFbc2-Z7D_r9v6x1SW6k"
  },
};

jQuery.ajax(settings).done(function (response) {
  console.log(response);
});
</script>

Still I am getting error please help for this

<script>

var requestOptions = {
  method: 'GET',
};

fetch("https://a.klaviyo.com/api/v2/list/------/members?api_key=API_KEY&emails=123@gmail.com", requestOptions)
.then(response => response.json())
.then(result => console.log(result))
.catch(error => console.log('error', error));

</script>

same cross-origin issue

This is happening because of the CORS (Cross Origin Resource Sharing) . For every HTTP request to a domain, the browser attaches any HTTP cookies associated with that domain. This is especially useful for authentication, and setting sessions. You are doing an XMLHttpRequest to a different domain than your page is on. So the browser is blocking it as it usually allows a request in the same origin for security reasons. You need to do something different when you want to do a cross-domain request.

JSONP ( JSON with Padding ) is a method commonly used to bypass the cross-domain policies in web browsers. You’re on domain example.com , and you want to make a request to domain example.nett . To do so, you need to cross domain boundaries. JSONP is really a simple trick to overcome the XMLHttpRequest same domain policy. So, instead of using XMLHttpRequest we have to use < script > HTML tags, the ones you usually use to load JavaScript files , in order for JavaScript to get data from another domain.

Localhost

If you need to enable CORS on the server in case of localhost, you need to have the following on request header.

Access-Control-Allow-Origin: http://localhost:9999