How can I pass POST parameters in fetch request? - React Native

Try to add header in post request.

       headers: {
         'Accept': 'application/json',
         'Content-Type': 'application/json',

       },
       body: JSON.stringify({
         wstoken: 'any_token',
         wsfunction: 'any_function',
         moodlewsrestformat: 'json',
         username: 'user',
         password: 'pass',
      })

This what worked for me

fetch("http://10.4.5.114/localservice/webservice/rest/server.php", {
  method: 'POST',
  headers: new Headers({
             'Content-Type': 'application/x-www-form-urlencoded', // <-- Specifying the Content-Type
    }),
  body: "param1=value1&param2=value2" // <-- Post parameters
})
.then((response) => response.text())
.then((responseText) => {
  alert(responseText);
})
.catch((error) => {
    console.error(error);
});