一、 自顶向下的编程形式
以骨干逻辑为开始,而后向下细分逻辑
function isPalindrome (s) { const filtereds = _filterNonNumberAndChar(s); const reverseds = _reverseString(filtereds); return _equalsIgnoreCase(filtereds, reverseds);}function _filterNonNumberAndChar(s) { return null}function _reverseString(s) { return null}function _equalsIgnoreCase(s, t) { return null}