connect-inject

0.4.0 verified Sat Apr 25 auth: no javascript deprecated

A Connect/Express middleware for injecting arbitrary script tags or content into HTML responses by intercepting res.write and res.end. v0.4.0 is the latest stable release; package appears unmaintained since 2015 (no recent commits, no changelog). Forked from connect-livereload, it adds support for multiple injection rules and array snippets. Unlike alternatives (e.g., inject-lr-script), it does not require a live-reload server and allows full snippet customization. Works with any Connect-compatible framework (Connect, Express, Grunt connect). Only notable differentiator is the `runAll` option for applying multiple injection rules sequentially.

Common errors

error TypeError: require('connect-inject') is not a function ↓

cause Calling the require result directly without invoking the factory function export.

fix

Add parentheses: require('connect-inject')()

error Cannot read property 'indexOf' of undefined ↓

cause The snippet option is missing or not provided when the middleware is invoked.

fix

Pass an options object with a snippet property: require('connect-inject')({ snippet: '...' })

error Snippet not injected into HTML response ↓

cause Response file extension is in the default ignore list (e.g., .html not ignored but .js, .css are; check if response has an extension that triggers ignore).

fix

Override ignore option: ignore: [] or remove unneeded entries.

Warnings

deprecated Package is unmaintained since 2015; no security updates or compatibility fixes for newer Node versions. ↓

fix Migrate to actively maintained alternatives like connect-livereload (original) or inject-lr-script.

gotcha Options object must be passed to the factory function call; passing the function itself to app.use will throw. ↓

fix Always call the function: app.use(require('connect-inject')({...})).

gotcha Ignore list defaults ignore .js, .css, .svg, etc. If your snippet injection isn't appearing, check that the response extension is not in the ignore list. ↓

fix Override the ignore option: ignore: [] to disable filtering.

gotcha The HTML detection function uses a regex that may misidentify non-HTML content as HTML, leading to unintended injection into JSON or other responses. ↓

fix Avoid using for non-HTML endpoints or provide a custom html option that checks Content-Type header.

gotcha Multiple rules with runAll: true apply sequentially; if a rule's match is modified by a previous rule, later rules may fail to match. ↓

fix Ensure rule matches are independent or order them appropriately (e.g., head before body).

Install

npm install connect-inject

yarn add connect-inject

pnpm add connect-inject

Imports

default
wrong
```
import inject from 'connect-inject';
```
correct
```
const inject = require('connect-inject');
```
Package is CommonJS only; no ESM wrapper. Using ES import will fail. Always use require.

default (with options)

wrong

require('connect-inject')(new Object({snippet: '<script>...</script>'}));

correct

const middleware = require('connect-inject')({ snippet: '...' });

Options object is passed directly to the factory function; no 'new' or constructor invocation.

default (no options)
wrong
```
app.use(require('connect-inject'));
```
correct
```
app.use(require('connect-inject')());
```
The factory must be called even without options; omit parentheses and the middleware won't be instantiated.

Quickstart

Demonstrates basic use of connect-inject middleware with Express, injecting two script tags into HTML responses.

const express = require('express');
const inject = require('connect-inject');
const app = express();

app.use(inject({
  snippet: ['<script src="/analytics.js"></script>', '<script>console.log("injected")</script>']
}));

app.get('/', (req, res) => {
  res.send('<html><body><h1>Hello</h1></body></html>');
});

app.listen(3000);