Express Normalize Query Params Middleware

0.5.1 verified Sat Apr 25 auth: no javascript

Express middleware that normalizes incoming query parameter names to be case-insensitive. Current stable version is 0.5.1, with low release cadence (last update likely pre-2018). Key differentiator: simple array-based whitelist approach, no dependencies, small footprint. Alternative to libraries like 'express-case-sensitive' or manual normalization. Note: only handles case normalization, not type coercion or default values.

Common errors

error TypeError: normalizeQueryParams is not a function ↓

cause Using ES6 import incorrectly with CommonJS require pattern.

fix

Use correct import: import normalizeQueryParams from 'express-normalize-query-params-middleware' or const normalizeQueryParams = require('express-normalize-query-params-middleware').default

error Cannot find module 'express-normalize-query-params-middleware' ↓

cause Package not installed or typo in package name.

fix

Run: npm install express-normalize-query-params-middleware

Warnings

gotcha The middleware only normalizes parameter names listed in the whitelist array; any extra params are left unchanged and case-sensitive. ↓

fix Ensure all expected parameters are included in the array passed to normalizeQueryParams.

gotcha The whitelist comparison is case-insensitive, but the result sets the key to the lowercase version of the whitelist entry, not the original incoming key. This may cause unexpected key naming if whitelist has mixed case. ↓

fix Always use lowercase strings in the whitelist to avoid confusion.

gotcha The middleware modifies req.query in place; if other middleware also modifies query, order matters. ↓

fix Place this middleware early in the stack, before any middleware that depends on normalized query params.

Install

npm install express-normalize-query-params-middleware

yarn add express-normalize-query-params-middleware

pnpm add express-normalize-query-params-middleware

Imports

default

wrong

const normalizeQueryParams = require('express-normalize-query-params-middleware').default

correct

import normalizeQueryParams from 'express-normalize-query-params-middleware'

ESM default import recommended. CommonJS require() works but .default may be needed depending on bundler.

default

const normalizeQueryParams = require('express-normalize-query-params-middleware')

CommonJS require() works directly, no need for .default.

TypeScript types
```
import normalizeQueryParams from 'express-normalize-query-params-middleware'
```
Package does not ship TypeScript definitions; consider using @types/express or custom type declaration.

Quickstart

Demonstrates basic usage: normalizes query params to lowercase keys based on whitelist.

import normalizeQueryParams from 'express-normalize-query-params-middleware';
import express from 'express';

const app = express();
const allowedParams = ['name', 'email', 'age'];
app.use(normalizeQueryParams(allowedParams));

app.get('/user', (req, res) => {
  // req.query.name, req.query.email, req.query.age are case-insensitive
  // e.g., ?Name=John&EMAIL=john@example.com works
  res.json(req.query);
});

app.listen(3000);