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";

const age = 18;
let mqlJson = jsmql`$.age > ${age} && $.status === "active"`
// → { $and: [{ $gt: ["$age", 18] }, { $eq: ["$status", "active"] }] }

mqlJson = 
    jsmql(($) => $.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"] } } }

mqlJson = 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" }
// ]

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 formatter handles long expressions
jsmql(($) => $.email.trim().toLowerCase().endsWith("@flash-payments.com"))

// Pipelines — write stages as a sequence, separated by `;`
jsmql(($) => {
  $match($.age >= 18 && $.region === "AU");      // → query doc, indexes still work
  $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)')
// compiles with $ifNull wrappers exactly where a null would crash a downstream operator.

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

// 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}}]

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

// Escape hatch — call any MongoDB operator directly
jsmql(($) => $dateTrunc({ date: $.createdAt, unit: "week" }))

// 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.
• Three call shapes — arrow jsmql(($) => …), string jsmql("…"), and template tag jsmql`…${val}…` for embedding outer-scope values.
• @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.
• $match indexes by default — index-safe predicates translate to query-document form; only the untranslatable parts fall back to $expr.
• Strict TS, strippable source — runs as-is on Node 24+, Deno, and Bun (no flags, no transpile).

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, mutation rules, $match query translation, jsmql.compile parameter semantics, 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