f receives a lower case string word and returns a product of primes that is the same for anagrams of that word

primeproduct.js

// https://twitter.com/fermatslibrary/status/958700402647674880
function f(word) {
    var primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71,73, 79, 83, 89, 97, 101];
    var product = 1;
    for (var i=0; i<word.length; i++) {
        product *= primes[word[i].charCodeAt(0)-97];
    }
    return product;
}

/*
f('a')  // 2
f('ab') // 6
f('ba') // 6
f('are') // 1342
f('ear') // 1342
f('undefinability') // 2513393075500633600
f('unidentifiably') // 2513393075500633600
*/