idempot-js

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Express ​

Installation ​

bash
npm install @idempot/express-middleware @idempot/sqlite-store

Usage ​

javascript
import express from "express";
import { idempotency } from "@idempot/express-middleware";
import { SqliteIdempotencyStore } from "@idempot/sqlite-store";

const app = express();
const store = new SqliteIdempotencyStore({ path: ":memory:" });

app.use(express.json());

app.post("/orders", idempotency({ store }), async (req, res) => {
  const orderId = crypto.randomUUID();
  res.status(201).json({ id: orderId, ...req.body });
});

app.listen(3000);

API ​

idempotency(options) ​

Creates Express middleware for idempotency.

Options:

  • store (required): Storage backend implementing IdempotencyStore
  • headerName: Header name for idempotency key (default: "Idempotency-Key")
  • required: Whether idempotency key is required (default: false)
  • ttlMs: Time-to-live for idempotency records in milliseconds
  • excludeFields: Fields to exclude from fingerprint calculation
  • resilience: Circuit breaker and retry options

Returns: Express middleware function with circuit property for monitoring.