Find closest object value via levenstein algo & JS proxy

find-closest-object-prop-via-proxy.js

// https://github.com/SiddharthShyniben/typosquatter
const peq = new Uint32Array(0x10000);
const myers_32 = (a, b) => {
    const n = a.length;
    const m = b.length;
    const lst = 1 << (n - 1);
    let pv = -1;
    let mv = 0;
    let sc = n;
    let i = m;
    while (i--)
        peq[b.charCodeAt(i)] = 0;
    i = n;
    while (i--)
        peq[a.charCodeAt(i)] |= 1 << i;
    for (i = 0; i < m; i++) {
        let eq = peq[b.charCodeAt(i)];
        const xv = eq | mv;
        eq |= ((eq & pv) + pv) ^ pv;
        mv |= ~(eq | pv);
        pv &= eq;
        if (mv & lst)
            sc++;
        if (pv & lst)
            sc--;
        mv = (mv << 1) | 1;
        pv = (pv << 1) | ~(xv | mv);
        mv &= xv;
    }
    return sc;
};
const myers_x = (b, a) => {
    const n = a.length;
    const m = b.length;
    const mhc = [];
    const phc = [];
    const hsize = Math.ceil(n / 32);
    const vsize = Math.ceil(m / 32);
    let score = m;
    for (let i = 0; i < hsize; i++) {
        phc[i] = -1;
        mhc[i] = 0;
    }
    let j = 0;
    for (; j < vsize - 1; j++) {
        let mv = 0;
        let pv = -1;
        const start = j * 32;
        const vlen = Math.min(32, m - start);
        let k = n;
        while (k--)
            peq[a.charCodeAt(k)] = 0;
        for (k = start; k < start + vlen; k++) {
            peq[b.charCodeAt(k)] |= 1 << k;
        }
        score = m;
        for (let i = 0; i < n; i++) {
            const eq = peq[a.charCodeAt(i)];
            const pb = (phc[(i / 32) | 0] >>> i % 32) & 1;
            const mb = (mhc[(i / 32) | 0] >>> i % 32) & 1;
            const xv = eq | mv;
            const xh = ((((eq | mb) & pv) + pv) ^ pv) | eq | mb;
            let ph = mv | ~(xh | pv);
            let mh = pv & xh;
            if ((ph >>> 31) ^ pb)
                phc[(i / 32) | 0] ^= 1 << i % 32;
            if ((mh >>> 31) ^ mb)
                mhc[(i / 32) | 0] ^= 1 << i % 32;
            ph = (ph << 1) | pb;
            mh = (mh << 1) | mb;
            pv = mh | ~(xv | ph);
            mv = ph & xv;
        }
    }
    let mv = 0;
    let pv = -1;
    const start = j * 32;
    const vlen = Math.min(32, m - start);
    let k = n;
    while (k--)
        peq[a.charCodeAt(k)] = 0;
    for (k = start; k < start + vlen; k++) {
        peq[b.charCodeAt(k)] |= 1 << k;
    }
    score = m;
    for (let i = 0; i < n; i++) {
        const eq = peq[a.charCodeAt(i)];
        const pb = (phc[(i / 32) | 0] >>> i % 32) & 1;
        const mb = (mhc[(i / 32) | 0] >>> i % 32) & 1;
        const xv = eq | mv;
        const xh = ((((eq | mb) & pv) + pv) ^ pv) | eq | mb;
        let ph = mv | ~(xh | pv);
        let mh = pv & xh;
        score += (ph >>> ((m % 32) - 1)) & 1;
        score -= (mh >>> ((m % 32) - 1)) & 1;
        if ((ph >>> 31) ^ pb)
            phc[(i / 32) | 0] ^= 1 << i % 32;
        if ((mh >>> 31) ^ mb)
            mhc[(i / 32) | 0] ^= 1 << i % 32;
        ph = (ph << 1) | pb;
        mh = (mh << 1) | mb;
        pv = mh | ~(xv | ph);
        mv = ph & xv;
    }
    return score;
};
function distance(a, b) {
    if (a.length < b.length) {
        const tmp = b;
        b = a;
        a = tmp;
    }
    if (b.length === 0)
        return a.length;
    if (a.length <= 32) {
        return myers_32(a, b);
    }
    return myers_x(a, b);
}
function closest(str, arr) {
    let min_distance = Infinity;
    let min_index = 0;
    for (let i = 0; i < arr.length; i++) {
        const dist = distance(str, arr[i]);
        if (dist < min_distance) {
            min_distance = dist;
            min_index = i;
        }
    }
    return arr[min_index];
}

const proxyGet = (obj, prop) => {
    if (!(prop in obj))
        prop = closest(prop, Object.getOwnPropertyNames(obj));
    return typeof obj[prop] === 'object' ?
        new Proxy(obj[prop], { get: proxyGet }) :
        new Proxy({ value: obj[prop] }, { get: primProxyGet });
};
const primProxyGet = (obj, prop) => {
    const prim = Reflect.get(obj, 'value');
    let value = prim[prop];
    if (!value) {
        prop = closest(prop, Object.getOwnPropertyNames(Object.getPrototypeOf('')));
        value = prim[prop];
    }
    if (typeof value === 'function')
        return value.bind(prim);
    return typeof value === 'object' ?
        new Proxy(value, { get: proxyGet }) :
        new Proxy({ value }, { get: primProxyGet });
};

const typosquatter = (obj) => new Proxy(obj, { get: typeof obj == 'object' ? proxyGet : primProxyGet });


let obj = typosquatter({foo: {bar: {baz: 'lol'}}});

console.log(obj.fo.ba.bz)