回文检查器（利用双端队列）

        function palindromeChecker(aString){
            if(aString === undefined || aString ===null || (aString !==null && aString.length === 0)){
                return false
            }
            const deque = new Deque(); //双端队列
            const lowerString = aString.toLowerCase().split(' ').join('')
            let isEqual = true;
            let firstChar,lastChar;
            for(let i=0;i<lowerString.length;i++){
                deque.addBack(lowerString,charAt(i));
            }
            while(deque.size()>1 && isEqual){
                firstChar = deque.romoveFront();
                lastChar = deque.romoveBack();
                if(firstChar !== lastChar){
                    isEqual = false;
                }
            }
            return isEqual
        }