express-processimage

11.2.0 verified Sat Apr 25 auth: no javascript

Express middleware for on-the-fly image processing based on query string parameters. Version 11.2.0. Intended for development use, not production. Supports multiple image formats (PNG, JPG, GIF, SVG) and operations (resize, pngcrush, optipng, jpegtran, svgfilter, etc.). Uses impro module to switch between backends (GraphicsMagick, ImageMagick, command-line tools). Alternative to separate build tools. Note: due to shelling out to external binaries, it presents security concerns; validate inputs and limit image sizes in production.

Common errors

error Error: spawn optipng ENOENT ↓

cause optipng binary not installed

fix

Install optipng via package manager (e.g., apt-get install optipng).

error TypeError: processImage is not a function ↓

cause Imported incorrectly (named instead of default)

fix

Use const processImage = require('express-processimage') or import processImage from 'express-processimage'.

error Error: Cannot find module 'impro' ↓

cause Missing dependency

fix

Run npm install express-processimage to install all dependencies.

error 403 Forbidden: no root set ↓

cause Root option not provided

fix

Add { root: '/path/to/images' } to processImage options.

Warnings

breaking Express 4.x requires app.use, not express().use() ↓

fix Use const app = express(); app.use(processImage({root})); app.listen(1337);

deprecated Option 'root' has been required since v5.0.0 ↓

fix Always pass { root: '/path' } object.

gotcha Middleware must be placed before express.static to intercept images ↓

fix Order: app.use(processImage({root})), then app.use(express.static(root)).

deprecated Query string tool names changed: 'optipng' deprecated in favor of 'pngcrush' ↓

fix Use 'pngcrush' instead of 'optipng'.

breaking Support for Node.js <10 removed in v8.0.0 ↓

fix Upgrade Node.js to v10 or higher.

gotcha ETag modification can cause caching issues with CDN ↓

fix Set cache-control headers explicitly.

Install

npm install express-processimage

yarn add express-processimage

pnpm add express-processimage

Imports

default

wrong

const processImage = require('express-processimage')

correct

import processImage from 'express-processimage'

CommonJS require works as default export

processImage

wrong

const { processImage } = require('express-processimage')

correct

const processImage = require('express-processimage')

No named export; default export only

default

wrong

import { processImage } from 'express-processimage'

correct

const processImage = require('express-processimage')

Must use default import

Quickstart

Set up Express server with express-processimage middleware to serve processed images via query parameters.

import express from 'express';
import processImage from 'express-processimage';
const app = express();
const root = '/path/to/images';
app.use(processImage({ root }));
app.use(express.static(root));
app.listen(3000);