Fetch: Can you pass parameters to the server

Question

I'm using a basic fetch to obtain data from an express server that queries the data from a database. So I want to do a login system, i want to send the user/password from the input fields with the fetch request. so i can perform the logical check to see if password matches the data in the server. and respond with the result. Is it possible to do a fetch that can pass parameters?

Updated Code Below:

let fetchData = {
  method: "post",
  headers: {
    'Accept': 'application/json',
    'Content-Type': 'application/json'
  },

  body: JSON.stringify({
    username: this.state.user,
    password: this.state.password
  })
}

var fromServer = fetch('http://localhost:3000/', fetchData)
.then(function(response){
  if( !response.ok){
    throw Error (response.statusText);
  }
  return response.json();
})
.then(function(response) {
  console.log(response);
})
.catch(error => console.log("there was an error --> " + error));

Express function

app.post('/', function(req, res){
  var uname = req.body.username;
  var pw = req.body.password;
  console.log(uname);
  console.log(pw);
});

Answer 1

Of course you can!

Here is an example of Fetch using a POST request:

fetch("http://example.com/api/endpoint/", {
  method: "post",
  headers: {
    'Accept': 'application/json',
    'Content-Type': 'application/json'
  },

  //make sure to serialize your JSON body
  body: JSON.stringify({
    name: myName,
    password: myPassword
  })
})
.then( (response) => { 
   //do something awesome that makes the world a better place
});

I've answered this question before, check this for more details:

POST Request with Fetch API?

To process the request in Express, as mentioned in your comment assuming your express server is setup to parse body requests, you can do this:

app.post('/your/route', function(req, res) {
    var name= req.body.name;
    var password = req.body.password;

    // ...do your bidding with this data
});