JavaScript scripting

Beyond plain SQL, a Query tab can run JavaScript against your live connection. Toggle the editor into script mode and write JS that queries the database with await db.query(...), loops, branches, and logs — useful for per-row work, small migrations, and quick data munging that’s awkward in a single statement.

Scripting works on SQL engines (PostgreSQL / MySQL / SQLite) and MongoDB. On SQL, db.query(...) takes SQL; on MongoDB it takes a mongo-shell command string (db.coll.find({…})). The toggle is hidden for Redis.

Switch a tab to scripting with the Lang picker in the editor toolbar (SQL → JavaScript); the run button becomes Run Script. console.log output appears in the Console strip below the results grid.

Writing a script

// Query returns an array of row objects.
const users = await db.query("SELECT id, email FROM users LIMIT 10");

for (const u of users) {
  // Per-row work, branching, anything JS can do.
  if (u.email.endsWith("@example.com")) {
    console.log(`internal user: ${u.id}`);
  }
}

// The last query's result (or a value you return) shows in the Data grid.
return users;

• await db.query(sql, params?) runs a query and resolves to an array of row objects ({ column: value, … }).
• console.log(...) output is captured and shown in the Console strip below the grid, in execution order.
• The returned value (or the last db.query result if you don’t return one) renders in the Data grid, exactly like a normal query.

MongoDB

On a MongoDB connection, db.query(...) takes a mongo-shell command instead of SQL — the same syntax the Query tab accepts (find, aggregate, insertOne, updateMany, …). The result is still an array of documents you can iterate:

const active = await db.query('db.users.find({ active: true })');
for (const u of active) {
  console.log(u.name);
}
return active;

Parameters are baked into the command object itself (there is no $1 placeholder binding for Mongo); build the filter/pipeline in the command string.

Parameters — always use db.query(sql, params)

Pass values as positional parameters ($1, $2, …) — they are bound by the driver, never string-interpolated, so there’s no SQL injection risk:

const email = "alice@example.com";
const rows = await db.query(
  "SELECT * FROM users WHERE email = $1",
  [email],
);

Do not build SQL by concatenating values into the string. Use params.

Stopping a script

A running script can be stopped two ways:

• Cancel — click the Cancel button (it replaces Run while a script is running). The engine stops at the next step.
• Timeout — scripts have a wall-clock timeout (30 seconds by default). A runaway loop such as while (true) {} is torn down automatically and the tab shows a “script timed out” error, so the app can’t hang.

What a script can and can’t do

• ✅ Query the database (db.query), loop, branch, console.log.
• ❌ No filesystem, network, or require/import — the sandbox exposes only db and console. Scripts can’t reach anything outside the database connection.
• Guards cap total rows and total queries per run, so an accidental unbounded loop terminates rather than exhausting memory.