js-db
A very tiny js in-memory database, using native JavaScript objects. Inspired by mongodb's syntax, even though it implements a subset of it.
Install
Using Node:
npm i @tducasse/js-dbOr in the browser:
<html>
<head>
<script src="https://unpkg.com/@tducasse/js-db/dist/umd/js-db.js"></script>
<script>
// the script is exported as 'jsdb'
jsdb.register("users")
jsdb.db.users.insert({name: "name"});
const user = jsdb.db.users.findOne();
console.log(user.name)
// "name"
</script>
</head>
</html>Docs
We basically export one object, called db, to which we attach collections using the register() function.
import { db, register } from "@tducasse/js-db";
// register the "users" collection
register("users");
// now you can call `db.users`
db.users.insert({ name: "John" });
const user = db.users.findOne({ name: "John" });
console.log(user);
// { name: "John" }register()
Registers a collection on the db object.
register("users");
// now you can access `users` on `db`
db.users.find();
// []seed()
Import initial data into the database. Also calls register() under the hood.
const items = {
users: [{ name: "John" }, { name: "Joe" }],
cities: [{ name: "Paris" }],
};
seed(items);
const users = db.users.find();
// [{ name: "John" }, { name: "Joe" }]
const cities = db.cities.find();
// [{ name: "Paris" }]reset()
Just a nice helper to reset the database. I mostly use it in tests though!
register("users");
// now you can access `users` on `db`
db.users.find();
// []
reset();
// db.users is now undefinedcollection.find()
Finds all the elements that match the query. Calling it without a query argument will just return everything.
register("users");
db.users.insert([{ name: "John" }, { name: "Joe" }]);
const users = db.users.find({ name: "John" });
// [{ name: "John" }]collection.count()
Like find(), except it just returns the number of elements that match the query. Again, calling it without any arguments will count everything.
register("users");
db.users.insert([{ name: "John" }, { name: "Joe" }]);
const count = db.users.find({ name: "John" });
// 1collection.findOne()
Finds the first (not sure about the order) element that matches the query. Calling it without a query argument will just return the first item (again, not really sure which).
register("users");
db.users.insert([{ name: "John" }, { name: "Joe" }]);
const users = db.users.findOne({ name: "John" });
// { name: "John" }collection.insert()
You've seen me use it already, but it does what it looks like: inserts the item(s) in the collection. Can be either an array or a single item.
register("users");
// works with an array
db.users.insert([{ name: "John" }, { name: "Joe" }]);
// or with a single element
db.users.insert({ name: "Mark" });collection.remove()
Removes all the elements that match the query.
register("users");
db.users.insert([{ name: "John" }, { name: "Joe" }]);
db.users.remove({ name: "John" });
const users = db.users.find();
// [{ name: "Joe" }]collection.update()
Updates every element that matches the query. Use $set for single value fields, and $push for array fields. $push and $set don't need the key to exist, they will create it if it doesn't.
register("users");
db.users.insert([{ name: "John" }, { name: "Joe", cities: [] }]);
// use $set for single value fields
db.users.update({ name: "John" }, { $set: { name: "Mark" } });
const users = db.users.find();
// [{ name: "Mark"}, { name: "Joe" }]
// and $push for array fields
db.users.update({ name: "Joe" }, { $push: { cities: "Melbourne" } });
const users = db.users.find();
// [{ name: "Mark"}, { name: "Joe", cities: ["Melbourne"] }]Note on the query/update object
You can access nested keys using the dot-notation syntax.
register("users");
db.users.insert({ name: "John" });
db.users.update({ name: "John" }, { $set: { "address.city": "Melbourne" } });
const users = db.users.find();
// [{ name: "John", address: { city: "Melbourne" }}]
const user = db.users.findOne({ "address.city": "Melbourne" });
// [{ name: "John", address: { city: "Melbourne" }}]Creating a shell
You can access the database in your code, importing the db object, but you can also create a separate npm script to run it through a Node repl.
// start a socket on 1337
net
.createServer((socket) => {
const r = repl.start({
prompt: "js-db>",
input: socket,
output: socket,
terminal: true,
preview: false,
});
// share the `db` object with the socket
r.context.db = db;
})
.listen(1337);// in cli.js
import net from "net";
const sock = net.connect(1337);
process.stdin.pipe(sock);
sock.pipe(process.stdout);
process.stdin.on("data", (b) => {
if (b.length === 1 && b[0] === 4) {
process.stdin.emit("end");
}
});// in package.json
{
"scripts:
// I use esm, but you get the idea
"cli": "node -r esm cli.js"
}Now, when you run npm run cli, you get a node interactive shell (with autocompletion, etc), in which you can access db.