refactor: extract helpers and improve input vals

apps/palindrome-checker/public/script.js

@@ -2,39 +2,54 @@ const userInput = document.getElementById('text-input');
 const checkPalindromeBtn = document.getElementById('check-btn');
 const resultDiv = document.getElementById('result');
 
-const checkForPalindrome = input => {
-  const originalInput = input; // Store for later output
-
-  if (input === '') {
-    alert('Please input a value');
-    return;
-  }
+// Normalize text by removing non-alphanumeric characters and lowercasing
+const normalizeText = str =>
+  str.replace(/[^A-Za-z0-9]/gi, '').toLowerCase();
+
+// Return true if the given text is a palindrome
+const isPalindrome = str => {
+  const normalized = normalizeText(str);
+  return normalized === [...normalized].reverse().join('');
+};
 
+const showResultMessage = message => {
   // Remove the previous result
   resultDiv.replaceChildren();
 
-  const lowerCaseStr = input.replace(/[^A-Za-z0-9]/gi, '').toLowerCase();
-  let resultMsg = `${originalInput} ${
-    lowerCaseStr === [...lowerCaseStr].reverse().join('') ? 'is' : 'is not'
-  } a palindrome.`;
-
   const pTag = document.createElement('p');
   pTag.className = 'user-input';
-  pTag.innerText = resultMsg;
+  pTag.textContent = message;
   resultDiv.appendChild(pTag);
 
-  // Show the result.
+  // Show the result
   resultDiv.classList.remove('hidden');
 };
 
-checkPalindromeBtn.addEventListener('click', () => {
+const checkForPalindrome = rawInput => {
+  const originalInput = rawInput; // Preserve for output
+  const input = rawInput.trim();
+
+  if (!input) {
+    showResultMessage('Please input a value.');
+    return;
+  }
+
+  const resultMsg = `${originalInput} ${
+    isPalindrome(input) ? 'is' : 'is not'
+  } a palindrome.`;
+
+  showResultMessage(resultMsg);
+};
+
+const handleCheck = () => {
   checkForPalindrome(userInput.value);
   userInput.value = '';
-});
+};
+
+checkPalindromeBtn.addEventListener('click', handleCheck);
 
 userInput.addEventListener('keydown', e => {
   if (e.key === 'Enter') {
-    checkForPalindrome(userInput.value);
-    userInput.value = '';
+    handleCheck();
   }
-});
+});