How to upload string as file with jQuery or other js framework

Question

Using javascript, I have a file in string (got with ajax request).

How to upload it as file to server by another ajax request ?

Answer 1

Here's how to do it without manually building the multi-part request body:

var s = 'some string data';
var filename = 'foobar.txt';

var formData = new FormData();
formData.append('file', new File([new Blob([s])], filename));
formData.append('another-form-field', 'some value');

$.ajax({
    url: '/upload',
    data: formData,
    processData: false,
    contentType: false,
    type: 'POST',
    success: function () {
        console.log('ok');
    },
    error: function () {
        console.log('err'); // replace with proper error handling
    }
});

Answer 2

Solution using new FormData() without ajax

str = "Hello!\nI'm text string";
var strblob = new Blob([str], {type: 'text/plain'});

var formdata = new FormData();
formdata.append("file", strblob, "file.txt");
formdata.append("field-1", "field-1-data");

var requestOptions = {
  method: 'POST',
  body: formdata,
  redirect: 'follow'
};

fetch("http://{url}", requestOptions)
  .then(response => response.text())
  .then(result => console.log(result))
  .catch(error => console.log('error', error))