jsmql

Write MongoDB aggregation queries in JavaScript. A strict JS subset that compiles to MQL JSON — like SQL but for MongoDB, using the syntax you already know.

import { jsmql } from "@koresar/jsmql";

// Filter — for db.coll.find(filter). No `;` at top level.
const age = 18;
let filter = jsmql`$.age > ${age} && $.status === "active"`
// → { age: { $gt: 18 }, status: "active" }   ← index-friendly query doc

// Pipeline — for db.coll.aggregate(pipeline). Any `;` flips to stage mode.
let pipeline = jsmql(($) => {
    $match($.status === "active");
    let subtotal = $.price * $.qty; // sub-total before tax/shipping
    let withTax  = subtotal * 1.2; // with tax
    $project({ sku: 1, subtotal, final: withTax });
});
// → [
//     { "$match": { "status": "active" } }
//     { "$set": { "__jsmql.subtotal": { "$multiply": ["$price", "$qty"] } } },
//     { "$set": { "__jsmql.withTax": { "$multiply": ["$__jsmql.subtotal", 1.2] } } },
//     {
//         "$project": {
//             "sku": 1,
//             "subtotal": "$__jsmql.subtotal",
//             "final": "$__jsmql.withTax"
//         }
//     },
//     { "$unset": "__jsmql" }
// ]

// Raw expression — for inside a stage body, or db.coll.updateOne(filter, update).
let expr = jsmql.expr(($) => $.items.map((i) => i.price * i.qty).reduce((a, x) => a + x, 0))
// → { $reduce: { input: { $map: { input: "$items", as: "i",
//     in: { $multiply: ["$$i.price", "$$i.qty"] } } },
//   initialValue: 0, in: { $add: ["$$value", "$$this"] } } }

MongoDB 8.0 deprecated server-side JavaScript via $function, $accumulator, and $where. The JSMQL is the replacement: native MQL, no --noscripting issues, index-friendly, IDE-aware, testable as plain JS.

Install

npm install @koresar/jsmql

ESM + CJS, runs in browsers, zero dependencies. Works with Node 14+, Deno, and Bun.

Tour

import "@koresar/jsmql/ops";          // ambient $-prefixed globals — autocomplete for 182 MQL ops & every stage
import { jsmql } from "@koresar/jsmql";

// Arrow form — your prettier/oxfmt handles formatting.
// No `;` at top level → query Filter (the doc db.coll.find(filter) takes).
jsmql(($) => $.email === $.email.trim().toLowerCase().endsWith("@flash-payments.com"))
// → {"$expr":{"$eq":["$email",{"$eq":[{"$substrCP":[{"$toLower":{"$trim":{"input":"$email"}}},{"$subtract":[{"$strLenCP":{"$toLower":{"$trim":{"input":"$email"}}}},{"$strLenCP":"@flash-payments.com"}]},{"$strLenCP":"@flash-payments.com"}]},"@flash-payments.com"]}]}}

// Pipelines — any `;` flips to stage mode (the array db.coll.aggregate(pipeline) takes).
jsmql(($) => {
  $match($.age >= 18 && $.region === "AU");      // → query doc, indexes still work
  $group({ _id: $.shopId, total: { $sum: $.amount } });
  $sort({ total: -1 });
});
// → [{ "$match": { "age": { "$gte": 18 }, "region": "AU" } }, { "$group": { "_id": "$shopId", "total": { "$sum": "$amount" } } }, { "$sort": { "total": -1 } }]

// Optional chaining is a real safety annotation, not a syntactic hint:
jsmql('[...$.mods, ...$.room?.mods, "root"].includes($.userId)')
//  { "$expr": { "$in": ["$userId", { "$concatArrays": ["$mods", { "$ifNull": ["$room.mods", []] }, ["root"]] }] } }
// compiles with $ifNull wrappers exactly where a null would crash a downstream operator.

// `new Date(...)` with literal args folds to a real JS Date — index-friendly query doc:
jsmql(`$.method === "postalDelivery" && $.createdAt >= new Date("2026-01-01")`)
// → { method: "postalDelivery", createdAt: { $gte: <Date 2026-01-01> } }
// `new Date()` and `new Date($.field)` still need server-time evaluation and ride in $expr.

// Template-tag — interpolate runtime literals from outer scope
const ids = [1, 2, 3];
jsmql`$.status === "open" && $.id in ${ids}`
// → { "status": "open", "$expr": { "$in": ["$id", [1, 2, 3]] } }

// jsmql.compile — parse once, bind many. Output stays index-friendly.
const eligible = jsmql.compile(({ minAge, region }, $) => {
  $match($.age >= minAge && $.region === region);
  $project({ age: 1, email: 1, address: 1 });
});
eligible({ minAge: 21, region: "AU" });
// → [{"$match":{"age":{"$gte":21},"region":"AU"}},{"$project":{"age":1,"email":1,"address":1}}]

// JS-natural `=`, `+=`, `delete` compile to coalesced $set / $unset
jsmql(($) => {
  $.score += 1;
  delete $.tempToken;
  $.status = "done";
});
// → [{ "$set": { "score": { "$add": ["$score", 1] } } }, { "$unset": "tempToken" }, { "$set": { "status": "done" } }]

// Assigning to bare `$` replaces the whole document — lowers to $replaceWith
jsmql(`$match($.profile != null); $ = $.profile; $ = { ...$, score: $.points * 1.1 }`);
// → [
//     { "$match": { "profile": { "$ne": null } } },
//     { "$replaceWith": "$profile" },
//     { "$replaceWith": { "$mergeObjects": ["$$ROOT", { "score": { "$multiply": ["$points", 1.1] } }] } }
//   ]

// Multi-facet aggregation — every value a `$$.filter(...)` lowers to one $facet stage
jsmql(`$ = {
  topByScore: $$.filter(o => { $sort({ score: -1 }); $limit(10); }),
  recent:     $$.filter(o => o.createdAt >= "2026-01-01"),
  byStatus:   $$.filter(o => { $group({ _id: o.status, n: $sum(1) }); })
}`);
// → [{ "$facet": {
//       "topByScore": [{ "$sort": { "score": -1 } }, { "$limit": 10 }],
//       "recent":     [{ "$match": { "createdAt": { "$gte": "2026-01-01" } } }],
//       "byStatus":   [{ "$group": { "_id": "$status", "n": { "$sum": 1 } } }]
//   } }]

// `jsmql()` returns an UpdateFilter as a pipeline, to avoid common footgun of wiping out the whole collection.
db.users.updateMany({}, jsmql(($) => $.name = $.name.toUpperCase()))
// → [{ "$set": { "name": { "$toUpper": "$name" } } }] -> will upper-case all names in the collection

// `jsmql.expr()` returns a partial MQL JSON. Won't protect from the same footgun.
db.users.updateMany({}, jsmql.expr(($) => $.name = $.name.toUpperCase()))
// → { "$set": { "name": { "$toUpper": "$name" } } } -> will WIPE OUT all names in the collection

// Strict-shape entry points — throw if the input would produce the wrong shape.
// Use these when the call site demands a specific shape and a silent
// mis-dispatch would be a footgun.
db.users.find(jsmql.filter("$.age > 18"));            // throws on Pipeline-shaped input
db.users.aggregate(jsmql.pipeline("$match($.age > 18); $sort({ age: 1 })")); // throws on bare expressions
db.users.updateOne({ _id: 1 }, jsmql.update("$.name = $.name.toUpperCase()"));
// update() additionally rejects any stage outside MongoDB's update-pipeline
// whitelist ($addFields, $project, $replaceRoot, $replaceWith, $set, $unset),
// so a misplaced `$match` is caught at compile time instead of at the server.

// Raw expression — for embedding inside a hand-written stage body
const stage = { $addFields: { discount: jsmql.expr(($) => $.price * (1 - $.loyalty.multiplier)) } }
// → { $addFields: { discount: { $multiply: ["$price", { $subtract: [1, "$loyalty.multiplier"] }] } } }

// Escape hatch — call any MongoDB operator as a function - $dateTrunc in this case
jsmql.expr(($) => $set({ createdAtWeek: $dateTrunc({ date: $.createdAt, unit: "week" }) }))
// → { $set: { "createdAtWeek": { "$dateTrunc": { "date": "$createdAt", "unit": "week" } } } }

jsmql(($) => $.age = 18); // generates a pipeline, to make sure you can use this in updateOne(), updateMany(), etc
// → [{ "$set": { "age": 18 } }]
jsmql.expr(($) => $.age = 18); // generates an partial expression, to use within OTHER aggregation or filter expressions
// → { "$set": { "age": 18 }

// Validate without throwing — every error carries { message, pos, code }
jsmql.validate(($) => $.age > 18)
// → { valid: true, errors: [] }

The live playground is the best place to see dozens of other JSMQL examples.

Why the arrow form

The arrow function is never executed — jsmql() calls Function.prototype.toString() on it, strips the parameter list, and parses the body. That single trick gives you:

• Formatting for free. Prettier, oxfmt, and every other JS formatter indent and line-break your query like any other JavaScript. No jsmql plugin, no custom config.
• Linting for free. ESLint, Biome, and your editor's TypeScript service see real JS — they flag typos, unused identifiers, and shape mismatches at write time.
• Code completion. With import "@koresar/jsmql/ops", your IDE autocompletes every stage and operator name, suggests the argument keys from the official MongoDB MQL spec, and surfaces the operator's description on hover.
• AI coding works out of the box. Copilot, Cursor, and Claude already know JavaScript — they autocomplete jsmql idiomatically because jsmql is JavaScript. There is no new vocabulary for them to learn.
• Pre-compilation. jsmql.compile() parses once, executes many times.

Highlights

• JS you already know — operators, ternaries, template literals, optional chaining, spread, computed keys, numeric separators, Math.*, Date, typeof, instanceof, comments. If node --check accepts it, jsmql does too.
• 182 operators, full coverage — every aggregation expression and accumulator from the official MongoDB MQL spec, including Bitwise and Window categories. Unknown operators pass through, so new MongoDB releases work day one.
• Plain MQL passes through. Drop hand-written MQL JSON inline — { $gt: ["$age", 18] }, a whole stage, a whole pipeline — and jsmql compiles it to itself. Mix the two freely, migrate one expression at a time, or paste verbatim from the MongoDB docs.
• Filter vs Pipeline picked automatically — a stage call ($match(...), $project(...), …) or an update op ($.x = …) at the top level lowers as a Pipeline (db.coll.aggregate(pipeline) / db.coll.updateOne(filter, update)); any ;-separated input lowers as a multi-stage Pipeline; everything else lowers as a Filter (db.coll.find(filter)). Index-safe predicates translate to query-document form; only the untranslatable parts ride in a top-level $expr. The naming follows the Node.js MongoDB driver's own Filter<TSchema> and pipeline parameter.
• Joins as JS — $$$.<coll>.find(pred) / $$$.<coll>.filter(pred) lower to $lookup stages, with predicate auto-translation to basic-form (localField/foreignField) or correlated-pipeline form. .find() follows JS semantics (scalar-or-null via $set { $first }); .filter() keeps the array. Chained .length, .reduce(fn, init), and member access compose inline. Block-body lambdas (o => { $match(...); $sort(...); $limit(N); }) become the full sub-pipeline body. $$$$.<db>.<coll>.find/filter(pred) covers the same surface for cross-database joins (uses MongoDB's from: { db, coll } shape — requires Atlas Data Federation). See docs/LANGUAGE.md → Cross-collection lookups.
• Collection unions as Array.push — $$.push({...}, ...$$$.<coll>.filter(pred), $$$.<other>.find(pred)) lowers to one or more $unionWith stages, with consecutive inline-doc args batched into a single $documents sub-pipeline. The spread (...) rule is JS-faithful: .filter and bare collections are arrays so they must be spread; .find and inline objects are scalars so they must not. $$$$.<db>.<coll> works for cross-database union (same Atlas caveat as cross-DB lookups). See docs/LANGUAGE.md → Collection union.
• Replace root as JS assignment — $ = <expr> lowers to $replaceWith (the lean MQL spelling for $replaceRoot: { newRoot: <expr> }): lift a sub-document ($ = $.profile), merge fresh fields ($ = { ...$, score: ... } — bare $ is the current document, like MQL's $$ROOT), or pivot to a joined doc ($ = $$$.users.find(pred)). Compile-time rejection points the user at the fix when the RHS obviously isn't a document (array literals, scalars, .filter() lookups). See docs/LANGUAGE.md → Replace root via $ = <expr>.
• Materialised views via $out — $$$.<coll> = $$ and $$$$.<db>.<coll> = $$ lower to a $out stage: the LHS names the destination, the RHS names the (optionally filtered) source. An inline $$.filter(<predicate>) on the RHS emits a $match before the write ($$$$.dw.archive = $$.filter(u => !u.active) → [{ $match: … }, { $out: { db: "dw", coll: "archive" } }]). Bracket form ($$$["my-coll.v2"] = $$) addresses collection names that aren't valid JS identifiers. The compiler enforces "$out must be last" at compile time. See docs/LANGUAGE.md → $out.
• $facet as a named object of filters — when every value of $ = { … } is a $$.filter(<lambda>), the same surface lowers to one $facet stage with each entry as a named sub-pipeline. Expression bodies become $match; block bodies become the block's stages. The lambda param is each input document (use o.<field>, not $.<field>). See docs/LANGUAGE.md → $facet via $ = { key: $$.filter(p), … }.
• Three call shapes — arrow jsmql(($) => …), string jsmql("…"), and template tag jsmql`…${val}…` for embedding outer-scope values.
• Polymorphic by default, strict on demand — jsmql() picks Filter or Pipeline from the input; jsmql.filter(), jsmql.pipeline(), and jsmql.update() lock it to one shape and throw an actionable error otherwise (with the offending stage named, for update()). jsmql.compile(fn) parses once for parameterised parse-once-bind-many. jsmql.expr() returns the raw aggregation expression that drops into a stage body. The three call shapes (string / arrow / template tag) apply to all of them.
• @koresar/jsmql/ops — a pure-types side-effect import that adds ambient $match / $dateAdd / … globals. Zero runtime cost; bundlers tree-shake it to nothing.
• Actionable errors — every error names the construct, suggests the nearest valid name (Did you mean '…'?), and carries a real .pos so editors can underline the offending region.
• Strict TS, strippable source — runs as-is on Node 22.18+ / 24.3+, Deno, and Bun (no flags, no transpile).

Using jsmql with mongoose

A one-shot registration patches the Model static methods so the standard find / updateOne / aggregate / … calls accept jsmql source directly, alongside the plain MQL-JSON forms you already pass them:

const mongoose = require("mongoose");
require("@koresar/jsmql/mongoose")(mongoose);
// or, ESM: import jsmqlMongoose from "@koresar/jsmql/mongoose"; jsmqlMongoose(mongoose);

const User = mongoose.model("User", new mongoose.Schema({ name: String, age: Number, score: Number }));

User.find("$.age > 18");                            // → find({ age: { $gt: 18 } })
User.find(($) => $.age > 18 && $.region === "AU"); // → find({ age: { $gt: 18 }, region: "AU" })

User.updateMany({}, ($) => $.score += 1);
// → updateMany({}, [{ $set: { score: { $add: ["$score", 1] } } }])

User.aggregate(($) => {
  $match($.status === "active");
  $group({ _id: $.region, total: { $sum: $.amount } });
  $sort({ total: -1 });
});

User.find({ age: { $gt: 18 } });                    // plain MQL JSON still passes through untouched

Detection rule. A patched argument is treated as jsmql source only when it's a string or a function. Plain objects/arrays (the regular MQL JSON forms) pass through to mongoose unchanged, so existing call sites need no migration. Template-tag inputs (jsmql\…``) lower to an object at the user's call site, so they take the pass-through path too.

TypeScript. The plugin ships a declare module "mongoose" augmentation that adds JSMQL-shaped overloads (string | JsmqlFn) to every patched Model static, so User.find("$.age > 18") and User.aggregate(($) => …) type-check after import "@koresar/jsmql/mongoose" — no per-call cast required. Mongoose's own FilterQuery<T> / UpdateQuery<T> overloads still apply on the MQL-JSON pass-through path.

Patched methods (with the slot used): find / findOne / findOneAnd{Delete,Replace,Update} / countDocuments / deleteOne / deleteMany / replaceOne / exists (filter at 0), updateOne / updateMany / findOneAndUpdate / findByIdAndUpdate (update at 1), distinct (filter at 1), aggregate (pipeline at 0). Each slot lowers through the matching strict-shape entry (jsmql.filter / jsmql.update / jsmql.pipeline), so a wrong-shape input — e.g. a bare expression at an aggregate slot — throws with the actionable strict-mode error at the patched call site instead of silently going wrong server-side. Registering twice on the same mongoose is a no-op.

See docs/specs/mongoose-plugin.md for the full per-slot table, the methods that are deliberately not patched (e.g. findOneAndReplace's replacement document), and the idempotence / subclass-propagation contracts.

Try it & learn more

• Live playground — write jsmql, see the MQL JSON update live. Pre-loaded with real-world recipes: tiered discounts, slug generation, audit logs, pivot tables, parameterised reports, and more.
• docs/LANGUAGE.md — the full language reference: every operator, every method, update-filter rules, $match query translation, jsmql.compile parameter semantics, jsmql.expr for raw aggregation expressions, the strict-shape entry points (jsmql.filter / jsmql.pipeline / jsmql.update), the @koresar/jsmql/ops import, error catalogue, server-side-JS migration guide.
• docs/DEVLOG.md — the running record of language decisions and the reasoning behind them.

License

MIT