JSFiddle - React, Tailwind, and code Playground

HTML

<form id="myForm" action="/" onsubmit="return submitFunction()">
  <div>
    column_1  <input type="text" name="column_1" value="" />
  </div>
   <div>
      column_2  <input type="text" name="column_2" value="" />
  </div>
   <div>
      column_3  <input type="text" name="column_3" value="" />
  </div>
  <button type="submit">
  Downloaduj CSV
  </button>
</form>

JavaScript

function submitFunction() {
  const formData = new FormData(document.getElementById('myForm'));
 	let csvContent = [];
  formData.forEach((value, key) => {
  	csvContent.push(`${key},${value}`);
  });
  csvContent = csvContent.join("\n");
  const blob = new Blob([csvContent], { type: 'text/csv;charset=utf-8;' });
  
  const link = document.createElement('a');
	link.href = URL.createObjectURL(blob);
	link.setAttribute('download', 'data.csv');
	document.body.appendChild(link);
	link.click();
	document.body.removeChild(link);
  return false;

}