:eq() selector implementation for native JavaScript's querySelectorAll

gistfile1.js

var querySelectorAllWithEq = function (selector) {
    if (selector === undefined) {
        return null;
    }
    var queue = [];
    var process = function (input) {
        if (input.indexOf(":eq(") === -1) {
            return undefined;
        }

        var eqlLoc = input.indexOf(":eq(");
        var sel = input.substring(0, eqlLoc);
        var ind = input.substring((eqlLoc + 4), input.indexOf(")", eqlLoc));
        selector = input.substring(input.indexOf(")", eqlLoc) + 1, input.length);

        if (sel.charAt(0) === ">") {
            sel = sel.substring(1, sel.length);
        }

        if (selector.charAt(0) === ">") {
            selector = selector.substring(1, selector.length);
        }

        queue.push({
            selector: sel,
            index: ind
        });
    }
    while (selector.indexOf(":eq") !== -1) {
        process(selector);
    }

    var result;
    while (queue.length > 0) {
        var item = queue.shift();
        result = (result || document).querySelectorAll(item.selector)[item.index];
    }

    if (selector.trim().length > 0) {
        return (result || document).querySelectorAll(selector);
    }
    return [result];
}