JavaScript Amerikan birimleri ve uluslararası birimler arasında değişiklik yapma

<script>
 // Function to update units based on user's preference.
 function updateUnits() {
 const unitsPreference = localStorage.getItem('unitsPreference');
 if (unitsPreference === 'international') {
 document.getElementById("flow").innerText = "m3/h";
 document.getElementById("total_head").innerText = "m";
 document.getElementById("static_head").innerText = "m";
 document.getElementById("u.i.p_head").innerText = "m";
 document.getElementById("a.s.n").innerText = "m";
 document.getElementById("m.i.p_head").innerText = "m";
 document.getElementById("power").innerText = "kW";
 document.getElementById("speed").innerText = "1/min";
 document.getElementById("temperature").innerText = "&lt;&#8451;";
 document.getElementById("density").innerText = "kg/dm3";
 document.getElementById("viscosity").innerText = "mm2/s";
 document.getElementById("pressure").innerText = "bar";
 document.getElementById("absolute_pressure").innerText = "bar";
 document.getElementById("dimensions").innerText = "mm";
 document.getElementById("velocity").innerText = "m/s";
 document.getElementById("volume").innerText = "m3";

 } else if (unitsPreference === 'american') {
 document.getElementById("flow").innerText = "US g.p.m";
 document.getElementById("total_head").innerText = "ft";
 document.getElementById("static_head").innerText = "ft";
 document.getElementById("u.i.p_head").innerText = "ft";
 document.getElementById("a.s.n").innerText = "ft";
 document.getElementById("m.i.p_head").innerText = "ft";
 document.getElementById("power").innerText = "hp";
 document.getElementById("speed").innerText = "rpm";
 document.getElementById("temperature").innerText = "&lt;&#8457;";
 document.getElementById("density").innerText = "lb/ft3";
 document.getElementById("viscosity").innerText = "ft2/s";
 document.getElementById("pressure").innerText = "psi";
 document.getElementById("absolute_pressure").innerText = "psi";
 document.getElementById("dimensions").innerText = "inch";
 document.getElementById("velocity").innerText = "ft/s";
 document.getElementById("volume").innerText = "US gal";
 }
 }
 // Run updateUnits() on page load and whenever the user's preference changes.
 window.onload = updateUnits;
 window.addEventListener('storage', updateUnits);
 </script>