javascript ObjectId generator

gistfile1.js

var mongoObjectId = function () {
    var timestamp = (new Date().getTime() / 1000 | 0).toString(16);
    return timestamp + 'xxxxxxxxxxxxxxxx'.replace(/[x]/g, function() {
        return (Math.random() * 16 | 0).toString(16);
    }).toLowerCase();
};

Impl in rust:

use chrono::Utc;
use rand::Rng;
use std::fmt;

fn mongo_object_id() -> String {
    let ts = Utc::now().timestamp_millis() / 1000;
    let mut id = format!("{:x}", ts);
    
    for _ in 0..16 {
        let random_digit = rand::thread_rng().gen_range(0..16);
        id.push_str(&format!("{:x}", random_digit));
    }

    id
}

fn main() {
    let object_id = mongo_object_id();
    println!("{}", object_id);
}

// [dependencies]
// chrono = "0.4"
// rand = "0.8"