【面试真题】Javascript 手写编程题

function isPalindrome(str) {  
  // 转换为小写并移除非字母字符  
  const cleanStr = str.toLowerCase().replace(/[^a-z]/g, '');  
  // 使用双指针法进行比较  
  let left = 0;  
  let right = cleanStr.length - 1;  
  while (left < right) {  
    if (cleanStr[left] !== cleanStr[right]) {  
      return false;  
    }  
    left++;  
    right--;  
  }  
  return true;  
}

function factorial(n) {  
  if (n === 0 || n === 1) {  
    return 1;  
  } else {  
    return n * factorial(n - 1);  
  }  
}

function flattenArray(arr) {  
  let result = [];  
  for (let i = 0; i < arr.length; i++) {  
    if (Array.isArray(arr[i])) {  
      result = result.concat(flattenArray(arr[i]));  
    } else {  
      result.push(arr[i]);  
    }  
  }  
  return result;  
}