In Javascript, you can make an HTTP request using the built-in XMLHttpRequest object or the newer fetch API.

Here's an example of making an HTTP GET request using XMLHttpRequest: 

const xhr = new XMLHttpRequest();
xhr.open('GET', 'https://example.com/api/data');
xhr.onload = function() {
  if (xhr.status === 200) {
    console.log(xhr.responseText);
  } else {
    console.log('Request failed.  Returned status of ' + xhr.status);
  }
};
xhr.send();

Here's an example of making an HTTP GET request using the fetch API:

fetch('https://example.com/api/data')
  .then(response => response.text())
  .then(data => console.log(data))
  .catch(error => console.error(error));

These examples show how to make a GET request, but you can also make other types of requests such as POST, PUT, DELETE, etc. by changing the method in the open function.