natural compare function

lexiSort.js

// benchmark: http://jsperf.com/natural-compare
"use strict";
function lexiSort(config) {
    return function (a, b) {
        if (typeof a === "number" && typeof b === "number")
            return a - b;
        if (a === null || b === null)
            return NaN;
        if (a === undefined || b === undefined)
            return NaN;
        if (Array.isArray(a) || Array.isArray(b))
            return NaN;
        if (typeof a === "object" || typeof b === "object") {
            if (!config && !config.keyFunc)
                return NaN;
            if (typeof a === "object")
                a = config.keyFunc(a);
            if (typeof b === "object")
                b = config.keyFunc(b);
        }
        if (typeof a !== "string" || typeof b !== "string")
            return a - b;
        if (a.length === 0 || b.length === 0)
            return a.length - b.length;
        var s1 = a, s2 = b, indexA = 0, indexB = 0, numberA, numberB, charA, charB, difference;
        do {
            numberA = 0;
            while (indexA < s1.length) {
                charA = s1[indexA];
                indexA++;
                if (!(charA >= "0" && charA <= "9"))
                    break;
                numberA = numberA * 10 + parseInt(charA);
            }
            numberB = 0;
            while (indexB < s2.length) {
                charB = s2[indexB];
                indexB++;
                if (!(charB >= "0" && charB <= "9"))
                    break;
                numberB = numberB * 10 + parseInt(charB);
            }
            if (charA === " " && charB === " ") {
                while (indexA < s1.length && s1[indexA] === " ") {
                    indexA++;
                }
                while (indexB < s2.length && s2[indexB] === " ") {
                    indexB++;
                }
            }
            difference = numberA - numberB;
            if (difference !== 0)
                return difference;
            if (charA !== charB) {
                if (charA === ".")
                    return -1;
                if (charB === ".")
                    return 1;
                return charA.toUpperCase().charCodeAt(0) - charB.toUpperCase().charCodeAt(0);
            }
        } while (indexA < s1.length && indexB < s2.length);
        return (indexB - s2.length) - (indexA - s1.length);
    };
}