How to properly convert curl command to Jquery Ajax

I have the following CURL Command which I want to convert to Jquery ajax but it alerts error Cannot get data

In the browser console. it shows error 401 Unathourized

I tried leveraging solution found here Source but still cannot get it to work

curl -X POST https://developer.expert.ai/oauth2/token \
    -H 'Content-Type: application/json; charset=utf-8' \
    -d '{
  "username": "yourusername",
  "password": "yourpassword"
}'

Here is the coding so far

$.ajax({
    url: "https://developer.expert.ai/oauth2/token",
    beforeSend: function(xhr) { 
      xhr.setRequestHeader('Content-Type', 'application/json; charset=utf-8'); 
    },
    type: 'POST',
crossDomain: true,
    dataType: 'json',
    contentType: 'application/json',
    processData: false,
data: JSON.stringify({
        'username': 'api username goes here',
        'password': 'api password goes here'
    }),
    success: function (data) {
      alert(JSON.stringify(data));
    },
    error: function(){
      alert("Cannot get data");
    }
});