three.js take 2 -- cryptopals

three.js

const xor = (str, key) =>
    Buffer.from(str, 'hex').map(byte => byte ^ key);

const getFreq = (str) =>
    str.toLowerCase().split('').reduce((result, item) => {result[item] = (result[item] || 0) + 1; return result}, {}); 

const weightFreq = (str) => {
    const letterWeights = {
        e: 0.12702,
        t: 0.09056,
        a: 0.08167,
        o: 0.07507,
        i: 0.06966,
        n: 0.06749,
        s: 0.06327,
        h: 0.06094,
        r: 0.05987,
        d: 0.04253,
        l: 0.04025,
        u: 0.02758
    };
    const len = str.length;
    const letterFreq = getFreq(str);
    const percentages = {};
    let score = 0;
    
    /*
     * find the % of each letter in the message
     */
    Object.keys(letterFreq).map(letter => { 
        percentages[letter] = letterFreq[letter] / len; 
    });

    /*
     * score the distance of ETAOIN SHRDLU
     */
    Object.keys(letterWeights).map(letter => { 
        if (!percentages.hasOwnProperty(letter)) {
            return false;
        }
        // score = absolute distance from percentages and weights
        score += Math.abs(letterWeights[letter] - percentages[letter]);
    });
    return score;
}

const findMessage = (msg) => {
    let start = 'a'.charCodeAt(0);
    let end = 'z'.charCodeAt(0);
    for (let i = start; i < (end + 1); i++) {
        console.log(i.toString() + ' (' + String.fromCharCode(i) + ')');
        // console.log(xor(msg, i)); // hex
        let msgStr = xor(msg, i).toString();
        console.log(weightFreq(msgStr));
        console.log(xor(msg, i).toString().toLowerCase());
    }
}

const msg = '1b37373331363f78151b7f2b783431333d78397828372d363c78373e783a393b3736';
findMessage(msg);
module.exports = weightFreq;