fetch api headers code example

Example 1: js fetch 'post' json

//Obj of data to send in future like a dummyDb
const data = { username: 'example' };

//POST request with body equal on data in JSON format
fetch('https://example.com/profile', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
  },
  body: JSON.stringify(data),
})
.then((response) => response.json())
//Then with the data from the response in JSON...
.then((data) => {
  console.log('Success:', data);
})
//Then with the error genereted...
.catch((error) => {
  console.error('Error:', error);
});

//																		Yeah

Example 2: Add no cores to fetch

// There were no quick access to mode and credentials to other fetch answers.
// Data you'll be sending
const data = { funny: "Absolutely not", educational: "yas" }

fetch('https://example.com/api/', {
  method: 'POST', // The method
  mode: 'no-cors', // It can be no-cors, cors, same-origin
  credentials: 'same-origin', // It can be include, same-origin, omit
  headers: {
    'Content-Type': 'application/json', // Your headers
  },
  body: JSON.stringify(data),
}).then(returnedData => {
  // Do whatever with returnedData
}).catch(err => {
  // In case it errors.
})

Example 3: fetch post json

(async () => {
  const rawResponse = await fetch('https://httpbin.org/post', {
    method: 'POST',
    headers: {
      'Accept': 'application/json',
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({a: 1, b: 'Textual content'})
  });
  const content = await rawResponse.json();

  console.log(content);
})();

Example 4: js fetch api

// Example POST method implementation:
async function postData(url = '', data = {}) {
  // Default options are marked with *
  const response = await fetch(url, {
    method: 'POST', // *GET, POST, PUT, DELETE, etc.
    mode: 'cors', // no-cors, *cors, same-origin
    cache: 'no-cache', // *default, no-cache, reload, force-cache, only-if-cached
    credentials: 'same-origin', // include, *same-origin, omit
    headers: {
      'Content-Type': 'application/json'
      // 'Content-Type': 'application/x-www-form-urlencoded',
    },
    redirect: 'follow', // manual, *follow, error
    referrerPolicy: 'no-referrer', // no-referrer, *no-referrer-when-downgrade, origin, origin-when-cross-origin, same-origin, strict-origin, strict-origin-when-cross-origin, unsafe-url
    body: JSON.stringify(data) // body data type must match "Content-Type" header
  });
  return response.json(); // parses JSON response into native JavaScript objects
}

postData('https://example.com/answer', { answer: 42 })
  .then(data => {
    console.log(data); // JSON data parsed by `data.json()` call
  });