cryptopals set 1 challenge 3

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: 12.702,
        t: 9.056,
        a: 8.167,
        o: 7.507,
        i: 6.966,
        n: 6.749,
        s: 6.327,
        h: 6.094,
        r: 5.987,
        d: 4.253,
        l: 4.025,
        u: 2.758
    };
    const tokens = str.toLowerCase().split(''); // this doesn't account for nonvalid tokens (whitespace / symbols / etc)
    const len = tokens.length;
    let weight = 0;
    for (let i=0; i < len; i++) {
        let token = tokens[i];
        weight += letterWeights[token] || 0; // rewrite w/ reduce
    }
    return len / weight;
}

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());
    }
}

const msg = '1b37373331363f78151b7f2b783431333d78397828372d363c78373e783a393b3736';
findMessage(msg);