JSFiddle - React, Tailwind, and code Playground

HTML

<table>
<tr>
  <td><input type='text' id='r1'> =&gt;</td>
  <td><input type='text' id='v1'></td>
</tr>
<tr>
  <td><input type='text' id='r2'> =&gt;</td>
  <td><input type='text' id='v2'></td>
</tr>
<tr><td colspan='2'><button onclick='replace()'>Заменить</button></td></tr>
</table>
<br><b>Результат:</b>
<div id='result'>
</div>

JavaScript

var array = ['BMW', 'Ваз', 'Газ', 'Паз'];

show_array();

function replace()
{
   var r1 = document.getElementById('r1').value,
       r2 = document.getElementById('r2').value,
       v1 = document.getElementById('v1').value,
       v2 = document.getElementById('v2').value;
   if ((pos = array.indexOf(r1)) != -1)
      array[pos] = v1;
   if ((pos = array.indexOf(r2)) != -1)
      array[pos] = v2;
   show_array();
}

function show_array()
{
   var el = document.getElementById('result'), out = '';
   for(var i in array)
      out += array[i] + '<br>';
   el.innerHTML = out;
}