"Ter aen larii uo.aer oaohhsb ehwkarc h ehJheeaenn t nrfi u ptomma etangdoyrds. pWv semse "

"T-er- -a---e-n--- -l---a-----r-i-----i--- -u---o-----.-----a-e-----r--- -o-----a---o-----"
"Ther- has-be-n -- -le-ha---w-rki---a-i--- -ur-co-----. ---ha-e ---er--- -o-h---a--Jo-h---" 
"There has-been a- ele-han--w-rkin- a-i--t -ur co---n-. ---ha-e r-fer--- -o-hi--a- Jo-hu--"
"There has been a- elephant-workin- ami--t -ur com-an-. -- ha-e refer--- to-hi--a- Jo-hua-"
"There has been an elephant-working amid-t our com-any. -- ha-e referr-d to-hi--as Jo-hua."
"There has been an elephant working amid-t our company. W- have referr-d to hi--as Jo-hua."
"There has been an elephant working amidst our company. W- have referred to him-as Joshua."
"There has been an elephant working amidst our company. We have referred to him-as Joshua."
"There has been an elephant working amidst our company. We have referred to him as Joshua."

"Epadtrp oarpnjsneisunaecriosdrasx h o htestov eblieert tonerstot  el  ttcnepa.et    htf  i pemtrou to parritetl aeft tkinenva hcn"

"E-pa-d-t---r-p--- -o---a-----r-p-----n---j-s---n-----e-----i-s-----u---n-a-----e---c-----r-------i---o-s---d-r---a-------------s-"
"Expa-d th- r-po-- -o -ha---t-rep---s-n---j-st-on-----ev--- i-se---bu---n-a-l---e--ic-e---r--e---ri-t-o-s---d r---at-----o------s-"
"Expand th- repor- so -hat--t-repo-ts-n-- j-st on---e-ev--- i-sel- bu---n-a-l --e-tic-et--r-ce---ri-t-ons---d r--eat-p---o--a---s."
"Expand the repor- so that -t repo-ts n-- j-st on -he-ev--t i-self bu---n a-l --e-tic-et -rice---ri-t-ons --d r-peat-pe--o-ma---s."
"Expand the report so that -t reports no- just on -he ev--t i-self but-on a-l --e tic-et price---riat-ons --d r-peat-per-orma---s."
"Expand the report so that it reports no- just on the eve-t itself but-on all --e tic-et price -ariat-ons --d repeat-performa---s."
"Expand the report so that it reports not just on the eve-t itself but on all t-e ticket price -ariations --d repeat-performan-es."
"Expand the report so that it reports not just on the event itself but on all t-e ticket price variations a-d repeat performan-es."
"Expand the report so that it reports not just on the event itself but on all the ticket price variations a-d repeat performances."
"Expand the report so that it reports not just on the event itself but on all the ticket price variations and repeat performances."

var str;

str = 'Thequickbrownfoxjumpsoverthelazydog';
//str = 'The quick brown fox jumps over the lazy dog.';
//str = 'There has been an elephant working amidst our company. We have referred to him as Joshua.';
//str = 'Expand the report so that it reports not just on the event itself but on all the ticket price variations and repeat performances.';

testIt(str);
moosh(str);

function moosh(input) {
    var str = shuffle(input.replace(/ /g, '')).split('');
    var output = input.split('').map(function (c) {
        return c === ' ' ? c : str.shift();
    }).join('');
    console.group('Moosh:');
    console.log('"' + input + '"');
    console.log('"' + output + '"');
    console.groupEnd();
}

function testIt(str) {
    console.group('Input string:');
    console.log('Input:', '"' + str + '"');

    console.group('Output:');
    shuffled = shuffle(str);
    unshuffled = unshuffle(shuffled);
    console.log('"' + shuffled + '"');
    console.log('"' + unshuffled + '"');
    console.groupEnd();
    console.groupEnd();
}

function unshuffle(str, showWorking) {
    var output = [];
    var remaining = str.split('');
    while (remaining.length) {
        var primes = [0].concat(primesUntil(remaining.length));
        var currentOutput = new Array(remaining.length).join('-').split('-');
        var current = remaining.splice(0, primes.length);

        for (var i = 0; i < primes.length; i++) {
            currentOutput[primes[i]] = current.shift();
        }

        if (output.length === 0) {
            output = currentOutput;
        } else {
            for (var j = 0; j < output.length; j++) {
                if (output[j] === '') {
                    output[j] = currentOutput.shift();
                }
            }
        }
    }

    return output.join('');
}

function shuffle(input) {
    var output = [],
        remaining = input.split('');
    while (remaining.length > 0) {
        var primeIndexed = [],
            nonPrimeIndexed = [];
        for (var i = 0; i < remaining.length; i++) {
            if (i === 0 || isPrime(i)) {
                primeIndexed.push(remaining[i]);
            } else {
                nonPrimeIndexed.push(remaining[i]);
            }
        }
        output = output.concat(primeIndexed);
        remaining = nonPrimeIndexed;
    }

    return output.join('');
}

function isPrime(n) {
    if (n == 2) {
        return true;
    } else if ((n < 2) || (n % 2 === 0)) {
        return false;
    } else {
        for (var i = 3; i <= Math.sqrt(n); i += 2) {
            if (n % i === 0) return false;
        }
        return true;
    }
}

function primesUntil(max) {
    var primes = [];
    for (var i = 0; i < max; i += 1) {
        if (isPrime(i)) {
            primes.push(i);
        }
    }
    return primes;
}

thequickbrownfox

theuc 12345.
onqik 67890.
rfbwo  12345.
x 6.
[1,2,3,5,7,11,13]
the.-u-c-.--o-n.---        (1)
…
qikr fbwox 1234 56789 [1,2,3,5,7]
qik.-r-.f--                       (2)
…
bwox [1,2,3]
bw.o-                               (3)
…
x [1]
x                                      (4)


Merge last into previous, taking up first available slot per character.
x
bwo- + x = bwox
qik.-r-.f-- + bwox = qikbrwfox
the.-u-c-.--o-n.--- + qikbrwfox
= the.quick.brown.fox