toTextBinary.js

var partialAny = (function() {
    var slice = Array.prototype.slice;

    function partialAny(fn /*, args...*/) {
        var orig = slice.call(arguments, 1);

        return function() {
            var partial = slice.call(arguments, 0);
            var args = [];
            for (var i = 0; i < orig.length; i++) {
                args[i] = orig[i] === partialAny._ ? partial.shift() : orig[i];
            }

            return fn.apply(this, args.concat(partial));
        }
    }

    partialAny._ = {};

    return partialAny;
}());

var compose = function(/* args... */) {
    var fns = arguments;

    return function(result) {
        for (var i = fns.length - 1; i > -1; i--) {
            result = fns[i].call(this, result);
        }

        return result;
    };
};

var __ = partialAny._;
var parseBinaryToInt = partialAny(parseInt, __, 2);

var toAsciiChar = compose(String.fromCharCode, parseBinaryToInt);

function charCode(ch) {
    if (!ch || ch.length > 1) {
        throw Error(ch + " is not a single char string")
    }
    return ch.charCodeAt(0);
}

function byteString(n) {
    if (n < 0 || n > 255 || n % 1 !== 0) {
        throw Error(n + " does not fit in a byte");
    }
    return ("000000000" + n.toString(2)).substr(-8)
}

var toBinaryChar = compose(byteString, charCode);

function toText(binaryStr) {
    return binaryStr.match(/.{1,8}/g).map(toAsciiChar).join('');
}

function toBinary(string) {
    return string.split('').map(toBinaryChar).join('');
}

console.log(
    toText(toBinary("sample"))
);