differ-cli

0.3.0 verified Thu Apr 23 auth: no javascript abandoned

differ-cli is a command-line interface (CLI) tool built with Node.js, designed to generate visual file differences. It relies on the 'universal-diff' library as its core diffing engine. Currently at version 0.3.0, the package appears to be unmaintained; its underlying 'universal-diff' library has not seen updates since its last commit in February 2015. Consequently, differ-cli utilizes older Node.js module patterns, specifically CommonJS `require`, and is not actively developed or receiving modern updates or security patches. Its primary function remains to compare the contents of two specified files and output their line-by-line differences directly to the console.

Common errors

error ReferenceError: require is not defined in ES module scope ↓

cause Attempting to use `require('differ-cli')` within an ES Module (ESM) file, or when `"type": "module"` is set in your `package.json`.

fix

This package is CommonJS only. You must use it in a CommonJS context. If your project is ESM, you may need to wrap the require call or use dynamic import import('differ-cli') if the package allowed it (which it might not fully support due to its age). The best fix is to use an ESM-compatible diffing library.

error differ is not a function ↓

cause This error can occur if `require('differ-cli')` does not return a function as expected, possibly due to an incorrect import, a changed API, or an environment issue.

fix

Verify that differ-cli is installed correctly and that require('differ-cli') indeed returns a function in your environment. Check for any global shims or conflicting package names.

Warnings

breaking The `differ-cli` package and its core dependency `universal-diff` have not been updated since 2015. This means there are no active maintainers, no new features, and no patches for bugs or potential security vulnerabilities. Using it in production is highly discouraged. ↓

fix Consider using actively maintained diffing libraries (e.g., `diff`, `js-diff`) or relying on built-in `git diff` functionality for modern projects.

gotcha This package is CommonJS-only and does not natively support ES Modules (`import`/`export` syntax). Attempting to import it directly in an ESM context without proper transpilation will lead to runtime errors. ↓

fix Ensure your project is configured for CommonJS, or use `require()` within an ESM wrapper if absolutely necessary. Prefer modern ESM-compatible alternatives.

gotcha Due to its age and lack of maintenance, `differ-cli` may not be compatible with newer Node.js versions, potentially leading to unexpected errors or silent failures. ↓

fix Test thoroughly in your target Node.js environment. If issues arise, migration to a current diffing library is recommended.

Install

npm install differ-cli

yarn add differ-cli

pnpm add differ-cli

Imports

differ
wrong
```
import differ from 'differ-cli';
```
correct
```
const differ = require('differ-cli');
```
This package is CommonJS-only. Attempting to use `import` syntax will result in a runtime error in a non-ESM Node.js environment or require specific configuration for transpilation.
CLI usage
wrong
```
node -e "require('differ-cli')('file1', 'file2')"
```
correct
```
npm install -g differ-cli
differ-cli <file1> <file2>
```
While programmatically possible, the primary intended use is directly via the installed global CLI command `differ-cli`.

Quickstart

This example demonstrates how to use `differ-cli` programmatically in a Node.js script to compare two temporary files and print the diff output to the console.

const fs = require('fs');
const path = require('path');
const differ = require('differ-cli');

const file1Path = path.join(__dirname, 'file1.txt');
const file2Path = path.join(__dirname, 'file2.txt');

// Create dummy files for demonstration
fs.writeFileSync(file1Path, 'Line 1\nLine 2\nLine 3 old\nLine 4\n');
fs.writeFileSync(file2Path, 'Line 1\nLine 2 modified\nLine 3 new\nLine 5 added\n');

differ(file1Path, file2Path, (err, result) => {
  if (err) {
    console.error('Error:', err);
  } else {
    console.log('Diff Result:\n', result);
  }
  // Clean up dummy files
  fs.unlinkSync(file1Path);
  fs.unlinkSync(file2Path);
});