https://www.npmjs.com/package/axios

Its Working

// "content-type": "application/x-www-form-urlencoded", // commit this

import axios from 'axios';

let requestData = {
      username : "abc@gmail.cm",
      password: "123456"
    };
   
    const url = "Your Url Paste Here";

    let options = {
      method: "POST",
      headers: { 
        'Content-type': 'application/json; charset=UTF-8',

        Authorization: 'Bearer ' + "your token Paste Here",
      },
      data: JSON.stringify(requestData),
      url
    };
    axios(options)
      .then(response => {
        console.log("K_____ res :- ", response);
        console.log("K_____ res status:- ", response.status);
      })
      .catch(error => {
        console.log("K_____ error :- ", error);
      });

fetch request

fetch(url, {
    method: 'POST',
    body: JSON.stringify(requestPayload),           
    headers: {
        'Content-type': 'application/json; charset=UTF-8',
        Authorization: 'Bearer ' + token,
    },
})
    // .then((response) => response.json()) .  // commit out this part if response body is empty
    .then((json) => {
        console.log("response :- ", json);
    }).catch((error)=>{
        console.log("Api call error ", error.message);
        alert(error.message);
});

 transformRequest: [
  function(data, headers) {
    headers["Content-Type"] = "application/json";
    return JSON.stringify(data);
  }
]

try this, it works

For me it worked using axios, typescript and form-data(v4.0.0):

import FormData from "form-data";
import axios from "axios";

async function login() {
  var data = new FormData();
  data.append("User", "asdf");
  const return = await axios.post(
    "https://ptsv2.com/t/1q9gx-1652805776/post", data,
    { headers: data.getHeaders() }
  );
  console.log(return);
}

In nodejs you can use URLSearchParams instead.

Like this:

  const formData = new URLSearchParams({
     param1: 'this',
     param2: 'is',
     param3: 'neat',
}); 

A boundary (which is used, by the server, to parse the payload) is set when the request is sent. You can't obtain the boundary before making the request. So, a better way to get this is using getBoundary() from your FormData.

var formData = new FormData();
formData.append('userName', 'Fred');
formData.append('file0', fileZero);
formData.append('file1', fileOne);

axios({
  method: "post",
  url: "myurl",
  data: formData,
  headers: {
      'Content-Type':  `multipart/form-data; ${formData.getBoundary()}`,
})
  .then(function (response) {
    //handle success
    console.log(response);
  })
  .catch(function (response) {
    //handle error
    console.log(response);
  });

The above method worked for me but since it was something I needed often, I used a basic method for flat object. Note, I was also using Vue and not REACT

packageData: (data) => {
  const form = new FormData()
  for ( const key in data ) {
    form.append(key, data[key]);
  }
  return form
}

Which worked for me until I ran into more complex data structures with nested objects and files which then let to the following

packageData: (obj, form, namespace) => {
  for(const property in obj) {
    // if form is passed in through recursion assign otherwise create new
    const formData = form || new FormData()
    let formKey

    if(obj.hasOwnProperty(property)) {
      if(namespace) {
        formKey = namespace + '[' + property + ']';
      } else {
        formKey = property;
      }

      // if the property is an object, but not a File, use recursion.
      if(typeof obj[property] === 'object' && !(obj[property] instanceof File)) {
        packageData(obj[property], formData, property);
      } else {
        // if it's a string or a File
      formData.append(formKey, obj[property]);
      }
    }
  }
  return formData;
}

In my case, the problem was that the format of the FormData append operation needed the additional "options" parameter filling in to define the filename thus:

var formData = new FormData();
formData.append(fieldName, fileBuffer, {filename: originalName});

I'm seeing a lot of complaints that axios is broken, but in fact the root cause is not using form-data properly. My versions are:

"axios": "^0.21.1",
"form-data": "^3.0.0",

On the receiving end I am processing this with multer, and the original problem was that the file array was not being filled - I was always getting back a request with no files parsed from the stream.

In addition, it was necessary to pass the form-data header set in the axios request:

        const response = await axios.post(getBackendURL() + '/api/Documents/' + userId + '/createDocument', formData, {
        headers: formData.getHeaders()
    });

My entire function looks like this:

async function uploadDocumentTransaction(userId, fileBuffer, fieldName, originalName) {
    var formData = new FormData();
    formData.append(fieldName, fileBuffer, {filename: originalName});

    try {
        const response = await axios.post(
            getBackendURL() + '/api/Documents/' + userId + '/createDocument',
            formData,
            {
                headers: formData.getHeaders()
            }
        );

        return response;
    } catch (err) {
        // error handling
    }
}

The value of the "fieldName" is not significant, unless you have some receiving end processing that needs it.

This should work well when needing to POST x-www-form-urlencoded data using axios from a NodeJS environment. You may need to add an Authorization header to the config.headers object if the endpoint requires authentication.

const config = {
  headers: {
    accept: 'application/json',
    'cache-control': 'no-cache',
    'content-type': 'application/x-www-form-urlencoded'
  }

const params = new URLSearchParams({key1: value1, key2: value2});

return axios
  .post(url, params.toString(), config)
  .then((response) => {
    return response.data;
  })
  .catch((error) => console.error(error));

I needed to upload many files at once using axios and I struggled for a while because of the FormData API:

// const instance = axios.create(config);

let fd = new FormData();
for (const img of images) { // images is an array of File Object
  fd.append('images', img, img.name); // multiple upload
}

const response = await instance({
  method: 'post',
  url: '/upload/',
  data: fd
})

I did NOT specify the content-type: multipart/form-data header!

i needed to calculate the content length aswell

const formHeaders = form.getHeaders();
formHeaders["Content-Length"] = form.getLengthSync()

const config = {headers: formHeaders}

return axios.post(url, form, config)
.then(res => {
    console.log(`form uploaded`)
})

I had the similar issues when using FormData with axios to make calls on https://apps.dev.microsoft.com service and it error-red out with "The request body must contain the following parameter: 'grant_type'"

After reformatting the data from

{
  grant_type: 'client_credentials',
  id: '123',
  secret: '456789'
}

to

"grant_type=client_credentials&id=123&secret=456789"

and the following code worked:

const config: AxiosRequestConfig = {
    method: 'post',
    url: https://apps.dev.microsoft.com/auth,
    data: 'grant_type=client_credentials&id=123&secret=456789',
    headers: {
        'Content-Type': 'application/x-www-form-urlencoded',
    }
};

axios(config)
.then(function (response) {
  console.log(JSON.stringify(response.data));
})
.catch(function (error) {
  console.log(error);
});

Even More straightforward:

axios.post('/addUser',{
    userName: 'Fred',
    userEmail: 'Flintstone@gmail.com'
})
.then(function (response) {
    console.log(response);
})
.catch(function (error) {
    console.log(error);
});

import axios from "axios";
import qs from "qs";   

const url = "https://yourapplicationbaseurl/api/user/authenticate";
    let data = {
      Email: "testuser@gmail.com",
      Password: "Admin@123"
    };
    let options = {
      method: "POST",
      headers: { "content-type": "application/x-www-form-urlencoded" },
      data: qs.stringify(data),
      url
    };
    axios(options)
      .then(res => {
        console.log("yeh we have", res.data);
      })
      .catch(er => {
        console.log("no data sorry ", er);
      });
  };

Using application/x-www-form-urlencoded format in axios

By default, axios serializes JavaScript objects to JSON. To send data in the application/x-www-form-urlencoded format instead, you can use one of the following options.

Browser

In a browser, you can use the URLSearchParams API as follows:

const params = new URLSearchParams();

params.append('param1', 'value1');

params.append('param2', 'value2');

axios.post('/foo', params);

Note that URLSearchParams is not supported by all browsers (see caniuse.com), but there is a polyfill available (make sure to polyfill the global environment).

Alternatively, you can encode data using the qs library:

const qs = require('qs');

axios.post('/foo', qs.stringify({ 'bar': 123 }));

Or in another way (ES6),

import qs from 'qs';

const data = { 'bar': 123 };

const options = {

  method: 'POST',

  headers: { 'content-type': 'application/x-www-form-urlencoded' },

  data: qs.stringify(data),

  url, };

axios(options);

2020 ES6 way of doing

Having the form in html I binded in data like so:

DATA:

form: {
   name: 'Joan Cap de porc',
   email: 'fake@email.com',
   phone: 2323,
   query: 'cap d\ou'
   file: null,
   legal: false
},

onSubmit:

async submitForm() {
  const formData = new FormData()
  Object.keys(this.form).forEach((key) => {
    formData.append(key, this.form[key])
  })

  try {
    await this.$axios.post('/ajax/contact/contact-us', formData)
    this.$emit('formSent')
  } catch (err) {
    this.errors.push('form_error')
  }
}

Upload (multiple) binary files

Node.js

Things become complicated when you want to post files via multipart/form-data, especially multiple binary files. Below is a working example:

const FormData = require('form-data')
const fs = require('fs')
const path = require('path')

const formData = new FormData()
formData.append('files[]', JSON.stringify({ to: [{ phoneNumber: process.env.RINGCENTRAL_RECEIVER }] }), 'test.json')
formData.append('files[]', fs.createReadStream(path.join(__dirname, 'test.png')), 'test.png')
await rc.post('/restapi/v1.0/account/~/extension/~/fax', formData, {
  headers: formData.getHeaders()
})

• Instead of headers: {'Content-Type': 'multipart/form-data' } I prefer headers: formData.getHeaders()
• I use async and await above, you can change them to plain Promise statements if you don't like them
• In order to add your own headers, you just headers: { ...yourHeaders, ...formData.getHeaders() }

Newly added content below:

Browser

Browser's FormData is different from the NPM package 'form-data'. The following code works for me in browser:

HTML:

<input type="file" id="image" accept="image/png"/>

JavaScript:

const formData = new FormData()

// add a non-binary file
formData.append('files[]', new Blob(['{"hello": "world"}'], { type: 'application/json' }), 'request.json')

// add a binary file
const element = document.getElementById('image')
const file = element.files[0]
formData.append('files[]', file, file.name)
await rc.post('/restapi/v1.0/account/~/extension/~/fax', formData)

Check out querystring.

You can use it as follows:

var querystring = require('querystring');
axios.post('http://something.com/', querystring.stringify({ foo: 'bar' }));

In my case I had to add the boundary to the header like the following:

const form = new FormData();
form.append(item.name, fs.createReadStream(pathToFile));

const response = await axios({
    method: 'post',
    url: 'http://www.yourserver.com/upload',
    data: form,
    headers: {
        'Content-Type': `multipart/form-data; boundary=${form._boundary}`,
    },
});

This solution is also useful if you're working with React Native.