version: "1.0.1" name: clickhouse-js-node-coding description: > Write idiomatic application code with the ClickHouse Node.js client (@clickhouse/client). Use this skill whenever a user is building against the Node.js client — configuring the client, pinging, inserting rows in JSON or raw formats, selecting and parsing results, binding query parameters, managing sessions and temporary tables, working with data types or customizing JSON parsing. Do NOT use for browser/Web client code.

ClickHouse Node.js Client — Coding

Reference: https://clickhouse.com/docs/integrations/javascript

⚠️ Node.js runtime only. This skill covers the @clickhouse/client

package running in a Node.js runtime exclusively — including **Next.js

Node runtime** API routes, React Server Components, Server Actions, and

standard Node.js processes. Do not apply this skill to browser client

components, Web Workers, Next.js Edge runtime, Cloudflare Workers, or

any usage of @clickhouse/client-web. For browser/edge environments, the

correct package is @clickhouse/client-web.

How to Use This Skill

1. Match the user's intent to a row in the Task Index below and read the

corresponding reference file before writing code. After reading it, scan any Answer checklist in that reference and make sure the final answer covers each relevant item; those checklists capture details users usually need but are easy to omit in short answers.

1. Always import from `@clickhouse/client` (never @clickhouse/client-web)

and create a client with createClient({ url }) or rely on supported defaults when appropriate. Close it with await client.close() preferably when it's no longer needed or during graceful shutdown for global resources.

1. Prefer `JSONEachRow` for typical row inserts/selects unless the user

has already chosen another format or is streaming raw bytes (CSV / TSV / Parquet — see examples/node/performance/). Note on `clickhouse_settings`: settings passed to createClient are defaults for every request; they can be overridden per-call by passing clickhouse_settings directly to insert(), query(), or command(). Always mention this when the user configures settings at the client level.

1. Always use `query_params` for user-supplied values — never template-

literal-interpolate them into SQL. See reference/query-parameters.md. When answering a parameter-binding question, your response must explicitly name template-literal interpolation as a "SQL injection risk" — even when the user only asked about syntax and did not raise security. The literal phrase "SQL injection" needs to appear; this is the most common mistake from PostgreSQL/MySQL users and the security framing is part of the correct answer, not an optional aside.

1. Pick the right method for the job:

• client.insert() — write rows.
• client.query() + resultSet.json() / .text() / .stream() — read

rows that return data.

• client.command() — DDL and other statements that don't return rows

(CREATE, DROP, TRUNCATE, ALTER, SET in a session, etc.).

• client.exec() — when you need the raw response stream of an arbitrary

statement (rare in coding scenarios).

• client.ping() — health check; returns { success, error? }, never

throws on connection failure.

1. Note version constraints when relevant. Examples:

• pathname config option: client >= 1.0.0.
• BigInt values in query_params: client >= 1.15.0.
• TupleParam and JS Map in query_params: client >= 1.9.0.
• Configurable json.parse / json.stringify: client >= 1.14.0.
• Time / Time64 data types: ClickHouse server >= 25.6.
• QBit data type: ClickHouse server >= 25.10 (GA on 26.x).
• Dynamic / Variant / new JSON types: ClickHouse server >= 24.1 /

24.5 / 24.8 (no longer experimental since 25.3).

Task Index

Identify the user's task and read the matching reference file.

Conventions used in answers

• Always show import { createClient } from '@clickhouse/client' (Node, never

Web).

• Always await client.close() at the end of self-contained snippets; in

long-running services, close on graceful shutdown.

• For inserts, prefer format: 'JSONEachRow' and values: [...] unless the

user's scenario requires otherwise.

• For selects, prefer await (await client.query({...})).json<RowType>() for

small / medium result sets; for bigger results suggest streaming.

• When showing parameter binding, use ClickHouse's native {name: Type}

syntax — never $1, ?, or :name.

• For DDL inside a cluster or behind a load balancer, set

clickhouse_settings: { wait_end_of_query: 1 } on the command() call so the server only acknowledges after the change is applied. See https://clickhouse.com/docs/en/interfaces/http/#response-buffering.

Out of scope

This skill covers day-to-day coding against @clickhouse/client (Node). The following topics are intentionally not covered here:

• **Errors, hangs, type mismatches, proxy pathname surprises, log silence,

socket hang-ups, ECONNRESET** → use the clickhouse-js-node-troubleshooting skill.

• **Streaming, Parquet, file streams, server-side bulk moves, progress

streaming, async-insert throughput tuning** — see `examples/node/performance/`.

• TLS, RBAC / read-only users, deeper SQL-injection guidance — see

`examples/node/security/`.

• **CREATE TABLE patterns, deployment-shaped connection strings,

replication / sharding choices** — see `examples/node/schema-and-deployments/`.

• Browser, Web Worker, Next.js Edge, Cloudflare Workers — use

@clickhouse/client-web and see `examples/web/`.

Still Stuck?

• `examples/node/coding/` — the runnable corpus this skill is built on.
• ClickHouse JS client docs
• ClickHouse supported formats
• ClickHouse data types