在 NodeJS 应用程序中发出 HTTP 请求时，何时显式设置标头

Question

So I was having a look at a codebase of a NodeJS application and there were some specific functions making HTTP requests to the backend. To be exact, those functions were making a GET request to the backend and one thing that I found confusing was that in some of the functions, the headers were mentioned explicitly whereas, in some other functions who were making the GET request, there was no mention of headers (ie headers were not being set explicitly). Below is an example:

In the code below, the function is making a GET request and there's no mention of headers (ie the headers are not being set explicitly):

// Method for fetching a single post from the backend on the basis of the post ID
export const singlePost = (postID) => {
  return fetch(http://localhost:8080/post/${postID}, {
    method: "GET",
  })
    .then((response) => {
      return response.json();
    })
    .catch((error) => {
      console.log(error);
    });
};

In the code below, the function is making a GET request and the headers are being set explicitly:

// Helper Method for making the call to the backend and fetching all their details of all the posts
export const list = (page) => {
  return fetch(http://localhost:8080/posts/?page=${page}, {
    method: "GET",
    headers: {
      Accept: "application/json",
      "Content-Type": "application/json",
    },
  })
    .then((response) => {
      return response.json();
    })
    .catch((error) => console.log(error));
};

Now coming to the main question, could someone please explain to me when are we supposed to set the headers explicitly not only in just GET request but in other general HTTP requests as well (ie POST, PUT, OPTION etc).

It would be really great if some could refer a source or explain this concept here. Thanks!

Answer 1

HTTP request header is the information, in the form of a text record, that a user's browser sends to a Web server containing the details of what the browser wants and will accept back from the server. The request header also contains the type, version and capabilities of the browser that is making the request so that server returns compatible data. Check this https://code.tutsplus.com/tutorials/http-headers-for-dummies--net-8039