我如何通过ajax对其余Web服务进行身份验证

Question

我想将用户名和密码发送到Rest Web服务以恢复令牌。我测试了此代码，但始终将我发送到错误功能

$.ajax({
  type: "POST",
  url: "http://192.168.1.89:1111/connect/token",
  dataType: 'json',
  async: false,
  data: '{}',
  beforeSend: function(xhr) {
    xhr.setRequestHeader('Authorization', btoa(username, password));
  },
  success: function() {
    alert('Thanks for your comment!');
  },
  error: function(xhr, status, error) {
    alert(error);
  }
});