修改JSONP请求的HTTP标头

var xhr = new XMLHttpRequest();
xhr.open('GET', 'http://example.com/jsonp?callback=?', true);
xhr.setRequestHeader('Content-Type', 'application/json');
xhr.onreadystatechange = function() {
  if (xhr.readyState == 4 && xhr.status == 200) {
    var json = JSON.parse(xhr.responseText.replace(/^\w+\(/, '').replace(/\)$/, ''));
    console.log(json);
  }
};
xhr.send();

$.ajax({
  url: 'http://example.com/jsonp',
  dataType: 'jsonp',
  jsonp: 'callback',
  success: function(data) {
    console.log(data);
  }
});

fetch('http://example.com/jsonp?callback=?', {
  method: 'GET',
  headers: {
    'Content-Type': 'application/json'
  }
})
  .then(response => response.text())
  .then(text => {
    const json = JSON.parse(text.replace(/^\w+\(/, '').replace(/\)$/, ''));
    console.log(json);
  });