valid-palindrome

Author: jun0811

valid-palindrome/jun0811.js

@@ -0,0 +1,32 @@
+var isPalindrome = function (s) {
+  let left = 0;
+  let right = s.length - 1;
+
+  while (left < right) {
+    while (left < right && !isAlphaNumeric(s[left])) {
+      left++;
+    }
+
+    while (left < right && !isAlphaNumeric(s[right])) {
+      right--;
+    }
+
+    if (s[left].toLowerCase() !== s[right].toLowerCase()) {
+      return false;
+    }
+
+    left++;
+    right--;
+  }
+
+  return true;
+};
+
+function isAlphaNumeric(char) {
+  const code = char.charCodeAt(0);
+  return (
+    (code >= 48 && code <= 57) || // 0-9
+    (code >= 65 && code <= 90) || // A-Z
+    (code >= 97 && code <= 122)
+  ); // a-z
+}