isPalindrome.js

//http://www.glassdoor.com/Interview/Given-a-large-input-string-write-a-function-to-check-if-it-is-a-palindrome-according-to-the-following-restrictions-low-QTN_927605.htm

//Given a large input string, write a function to check if it is a palindrome, 
//according to the following restrictions: -lowercase and uppercase characters are considered equal -special characters are ignored 

var aCode = "a".charCodeAt(0);
var ACode = "A".charCodeAt(0);
var setLen = 26;

function isChar(char) {
    var code = char.charCodeAt(0);
    return ((code >= aCode) && ((code - aCode) < setLen)) ||
           ((code >= ACode) && ((code - ACode) < setLen));
}

function normalizedCharCode(char) {
    var code = char.charCodeAt(0);

    if (!isChar(char)) {
        return -1;
    }

    if ((code >= ACode) && ((code - ACode) < (setLen - 1))) {
        return (code - ACode);
    }

    return code - aCode;
}

function isPalindrome(str) {
    var start = 0;
    var end = str.length - 1;

    while (start < end) {
        var startCode = normalizedCharCode(str[start]);

        if (startCode === -1) {
            start++;
            continue;
        }

        var endCode = normalizedCharCode(str[end]);

        if (endCode === -1) {
            end--;
            continue;
        }

        if (startCode !== endCode) {
            return false;
        }

        start++;
        end--;
    }

    return true;
}

console.log(isPalindrome("abc*(c/B;}{A"));