"This feature only runs on my computer."

Dependency on Personal Environment ("This feature only runs on my computer")

Some code is like a meticulously crafted cocktail, only revealing its perfect flavor in a specific environment. This type of code has an almost obsessive requirement for its runtime environment—it stops working the moment it leaves the developer's personal machine. It’s like a pumpkin carriage under a spell, reverting to its true form at the stroke of midnight.

The Magic Trap of Environment Variables

// A perfect case of environment variable dependency
function connectToDatabase() {
  const password = process.env.DB_PASSWORD || 'mySecretPassword123';
  const connection = new DatabaseConnection({
    host: 'localhost',
    user: 'dev_user',
    password: password
  });
  return connection;
}

This code contains at least three magical ingredients: a hardcoded localhost address, a default dev user account, and that elegant fallback password. When deployed to production, it will be as futile as searching for a Wi-Fi signal in the desert. Even better, the developer provided no documentation for environment variable configuration, leaving the next person to decipher it like a puzzle game.

The Death Dance of Absolute Paths

// The absolute art of file paths
import { userSettings } from 'C:/Users/DevUser/projects/app/src/config/settings.js';

function loadUserPreferences() {
  return userSettings.get('preferences');
}

This approach ensures the code only runs in a specific directory on the developer’s machine. When teammates try to clone the repository, it’s like navigating an unfamiliar city with the wrong map. Windows users struggle with backslashes, while Mac users are completely lost in the path forest.

The Black Box of Local Services

// Reliance on locally running microservices
async function fetchProductData(productId) {
  const response = await fetch('http://localhost:3001/api/products/' + productId);
  if (!response.ok) throw new Error('Product not found');
  return response.json();
}

This function assumes the product service is running on local port 3001 with the exact API path. When deployed to a test environment, it loses connection like a kite with a severed string. Even better, there’s no error handling or retry mechanism—just a cryptic error message upon failure.

The Secret Dependency on Browser Extensions

<template>
  <div v-if="$chrome && $chrome.storage">
    <!-- Chrome extension-exclusive functionality -->
  </div>
</template>

<script>
export default {
  mounted() {
    this.$chrome.storage.local.get(['userToken'], result => {
      this.token = result.userToken || 'default_token';
    });
  }
}
</script>

This Vue code quietly depends on Chrome extension APIs but behaves like a mime artist in a regular browser—utterly silent. There’s no fallback, no feature detection, just silent failure and a confused UI.

The Mysterious Ritual of Global Variables

// Assuming some mysterious script has injected these globals
function initializeApp() {
  if (!window.__APP_CONFIG__) {
    window.__APP_CONFIG__ = { 
      apiUrl: 'http://localhost:8080',
      debugMode: true 
    };
  }
  
  const apiClient = new ApiClient(window.__APP_CONFIG__.apiUrl);
  // ...
}

This code creates its own parallel universe where global variables exist as naturally as air. When placed in a clean page environment, it reacts like a deep-sea fish in freshwater—immediate discomfort.

The Uncommitted Config File Party

// .env.local (ignored by .gitignore)
DB_HOST=127.0.0.1
DB_USER=root
DB_PASS=toor

// database.js
require('dotenv').config();
const connection = mysql.createConnection({
  host: process.env.DB_HOST,
  user: process.env.DB_USER,
  password: process.env.DB_PASS
});

This classic case leaves critical configuration in the developer’s local environment file, generously ensuring it never enters version control via .gitignore. New developers running the project are like users with an appliance manual missing—they know it should work but can’t get it to start.

The Magic Annotations of a Specific IDE

// @webstorm-optimize
function expensiveCalculation(input: number[]): number {
  // Relies on WebStorm's type inference plugin
  return input.reduce((acc, val) => acc + (val * 2), 0);
}

This code contains magical annotations only understood by a specific IDE, appearing as cryptic as ancient inscriptions in other editors. Team members using different editors see red squiggles everywhere, as if the code is warning them.

The Maze Design of Local Storage

function getAuthToken() {
  const rawData = localStorage.getItem('appAuth');
  // Only the original author knows the data format
  try {
    const data = JSON.parse(rawData);
    return data.token || data.auth.token || data.session.authToken;
  } catch {
    return null;
  }
}

This function creates an intricate maze of storage structures, with the token potentially hidden anywhere in a three-layer nested object. Even better, there’s no migration strategy when the data structure changes—like changing the lock without providing a new key.

The Hidden Assumption of System Timezone

function generateReportDate() {
  const now = new Date();
  // Assumes the runtime timezone is always Asia/Shanghai
  return `${now.getFullYear()}-${now.getMonth()+1}-${now.getDate()}`;
}

This code has unwavering faith in timezones, believing the entire world follows the developer’s local timezone. When overseas users use the feature around midnight, they’ll see the date magically jump.

Dependency on Specific Host Page Structure

function injectSidebar() {
  // Assumes the page has a div with id="main-content"
  const container = document.getElementById('main-content');
  container.insertAdjacentHTML('afterend', sidebarHTML);
  
  // Also assumes this div has a specific CSS class
  document.querySelector('.page-container').classList.add('has-sidebar');
}

This code is like a precision lock that only fits a specific door shape. When the host page structure changes, the injection logic jams like misaligned gears.

Undocumented Build Steps

# Secret build commands only the developer knows
npm run build && npm run magic-optimize -- --env=dev

The project hides build steps like alchemy recipes—undocumented and existing only in the developer’s muscle memory. New members running standard build commands get output resembling a half-baked cake—close, but not quite right.

Syntax Sugar for Specific Node Versions

// Requires Node 16+ top-level await
const config = await loadConfig();
export default {
  plugins: [new AwesomePlugin(config)]
};

This module uses features from newer Node versions, but the engines field in package.json remains silent. When run on older versions, the error messages are as cryptic as riddles.

The Private Party of Local Font Files

/* Uses fonts only installed on the developer's machine */
@font-face {
  font-family: 'MyCoolFont';
  src: local('CoolFont Pro'), local('CoolFont-Pro');
  font-weight: normal;
}

body {
  font-family: 'MyCoolFont', sans-serif;
}

This CSS throws an exclusive font party, inviting only fonts installed on the developer’s system. On other machines, the page politely falls back to default fonts—though designers might have a heart attack upon seeing it.

The Stealthy Judgment of System Language

function getWelcomeMessage() {
  // Only checks navigator.language
  if (navigator.language.startsWith('zh')) {
    return '欢迎';
  }
  return 'Welcome';
}

This "internationalization" solution is brutally simple, assuming all Chinese users prefer simplified characters and the same greeting. Traditional Chinese users receive a welcome that seems correct but feels slightly off.

The Secret Pact with Hardware Acceleration

function start3DRendering() {
  // Relies on specific GPU features
  const canvas = document.getElementById('gameCanvas');
  const gl = canvas.getContext('webgl2', {
    powerPreference: 'high-performance'
  });
  
  if (!gl) {
    throw new Error('Your computer is too weak');
  }
}

This code strikes a secret deal with the developer’s high-end GPU, throwing discriminatory errors on other devices. There’s no progressive enhancement, no graceful degradation—just a cold rejection.