murmur collision tests

index.js

var fnvplus = require('fnv-plus');
var murmur = require('murmur');

function collisionRate(bits) {
    var hashes = {};
    var texts = 0;
    var collisions = [];
    var sample = 1e6;
    console.time(bits + ' bits');
    while (texts < sample) {
        var name = Math.random().toString(36);
        var num = parseInt(murmur.hash128(name).hex().substr(-1*(bits/4)), 16);
        if (hashes[num] === name) {
            continue;
        } else if (hashes[num]) {
            collisions.push([hashes[num], name]);
        } else {
            hashes[num] = name;
        }
        texts++;
    }
    console.timeEnd(bits + ' bits');
    console.log('%d bits, collisions: %s% (%s/%s)', bits, (collisions.length/sample * 100).toFixed(3), collisions.length, sample);
}

collisionRate(32);
collisionRate(52);

// 32 bits: 10440ms
// 32 bits, collisions: 0.011% (110/1000000)
// 52 bits: 12697ms
// 52 bits, collisions: 0.000% (0/1000000)

package.json

{
    "name": "murmur-collisions",
    "dependencies": {
        "murmur": "0.0.2"
    }
}