diff --git a/src/calculator/index.html b/src/calculator/index.html
index 1be4fe3..0f330c2 100644
--- a/src/calculator/index.html
+++ b/src/calculator/index.html
@@ -13,6 +13,6 @@
         }
     </style>
 
-    <input type="number" min="0" placeholder="your ASN" oninput="calculate(this)">
+    <input type="number" min="0" placeholder="your ASN" oninput="onAsnInput(this)">
     <p>Port: <span id="result"></span></p>
 </html>
\ No newline at end of file
diff --git a/src/calculator/script.js b/src/calculator/script.js
index 998cbbc..3594755 100644
--- a/src/calculator/script.js
+++ b/src/calculator/script.js
@@ -1,18 +1,22 @@
-const result = document.getElementById('result');
+function onAsnInput(inputElement) {
+    let portElement = document.getElementById('result');
 
-function calculate(el) {
-    if (el.value == '') {
-        result.innerText = '';
+    if (inputElement.value == '') {
+        portElement.innerText = '';
         return;
     }
 
-    let cand = cyrb53(el.value).toString().slice(0, 5);
+    portElement.innerText = calculate(inputElement.value);
+}
+
+function calculate(asn) {
+    let result = cyrb53(asn).toString().slice(0, 5);
         
-    if (cand > 65535 || cand < 30000) {
-        cand = (cand % 3 + 3) * 10000 + (cand % 10000);
+    if (result > 65535 || result < 30000) {
+        result = (result % 3 + 3) * 10000 + (result % 10000);
     }
 
-    result.innerText = cand;
+    return result;
 }
 
 // https://github.com/bryc/code/blob/master/jshash/experimental/cyrb53.js