Registry / web-framework / express-query-parser

express-query-parser

library1.3.3jsnpmunverified

An Express.js middleware that automatically parses and transforms query string values from strings to native JavaScript types: null, undefined, boolean, and number. Version 1.3.3 (May 2022) adds empty string conversion. It recursively handles nested objects and arrays. Compared to alternatives like qs (used by Express by default), this package provides a focused, zero-dependency solution with TypeScript type declarations and an ESBuild-based bundle, updated periodically since 2018.

web-framework

npm install express-query-parser

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INSTALL

IMPORT

SIG · EXPRESS-QUERY-PARS

express-query-parser

web-frameworkjavascriptv1.3.3

Install

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Import

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Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

queryParser

✓ import { queryParser } from 'express-query-parser'

✗ const queryParser = require('express-query-parser')

Named export; package supports both ESM and CJS.

queryParser

✓ const { queryParser } = require('express-query-parser')

✗ const queryParser = require('express-query-parser').default

CJS users must destructure the named export; no default export exists.

QueryParserOptions

✓ import type { QueryParserOptions } from 'express-query-parser'

✗ import { QueryParserOptions } from 'express-query-parser'

TypeScript users should import types with 'type' keyword to avoid runtime inclusion.

Demonstrates basic setup of the queryParser middleware with all parsing options enabled and shows the transformed query object.

import express from 'express'; import { queryParser } from 'express-query-parser'; const app = express(); app.use( queryParser({ parseNull: true, parseUndefined: true, parseBoolean: true, parseNumber: true }) ); app.get('/', (req, res) => { // GET /?a=null&b=true&c=3.14&d[]=false&d[]=undefined // req.query will be: { a: null, b: true, c: 3.14, d: [false, undefined] } res.json(req.query); }); app.listen(3000, () => { console.log('Server listening on port 3000'); });

Debug

Known issues

gotchaParsing options are not part of the user-facing API and cannot be omitted; invalid options object shape will cause fallback to defaults.

fix

Always pass an options object even if all defaults are used: queryParser({ parseNull: true, parseUndefined: true, parseBoolean: true, parseNumber: true })

affects: >=1.0.0

gotchaThe middleware does not modify the original req.query object; it creates a new one. This may affect references stored elsewhere.

fix

Access parsed values via req.query after middleware runs. Do not rely on previous references.

affects: >=1.0.0

gotchaEmpty strings are converted to null (since v1.3.3). This may break code expecting empty strings.

fix

Handle null checks or disable parseNull if you need to preserve empty strings.

affects: >=1.3.3

gotchaNumber conversion uses JavaScript's Number() function; scientific notation like '1e2' becomes 100. May produce NaN for non-numeric strings.

fix

Set parseNumber: false if you want to keep numeric strings as strings, or validate numeric strings before parsing.

affects: >=1.3.0

deprecatedThe package has not been updated since May 2022. No major bugs or CVEs reported, but it's in low-maintenance mode.

fix

Consider alternatives like qs with custom decoder or a more actively maintained parser.

affects: >=1.3.3

Errors

Common errors & fixes

TypeError: queryParser is not a function

Default import used instead of named import in ESM environment.

fix

Use named import: import { queryParser } from 'express-query-parser'

req.query is undefined after using queryParser

Middleware is executed after route handler or not applied at all.

fix

Ensure app.use(queryParser(...)) is called before any routes.

Expected null but got 'null' string

parseNull option is disabled (default is true, but may be overridden).

fix

Set parseNull: true in options, or explicitly check version compatibility.

Number '0' is converted to 0, but I wanted to keep it as string

parseNumber is enabled by default.

fix

Disable parseNumber: false if you need to preserve numeric strings.

Upgrade

Version history

1.3.3latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

4 hits · last 30 days

node

Resources

packagehttps://www.npmjs.com/package/express-query-parser ↗