WordPress Dev Interview Guide

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## 🟢 BASIC LEVEL

### 1. **What is WordPress?**
**Answer**: WordPress is an open-source CMS (Content Management System) built on PHP and MySQL. It enables users to create, manage, and publish content via a web interface.

### 2. **What are posts and pages in WordPress?**
**Answer**:
– **Posts** are timely blog entries or articles listed in reverse chronological order.
– **Pages** are static and used for timeless content like "About" or "Contact".

### 3. **What are themes and plugins in WordPress?**
**Answer**:
– **Themes** control the appearance and layout of a WordPress site.
– **Plugins** add extra functionality without altering the core.

### 4. **Where is `wp-config.php` used for?**
**Answer**: It contains database credentials, table prefix, debugging settings, and security keys.

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## 🟡 INTERMEDIATE LEVEL

### 5. **What are custom post types and taxonomies?**
**Answer**:
– **Custom Post Types (CPT)**: Allow creation of different types of content (e.g., `portfolio`, `testimonials`).
– **Taxonomies**: Used to group content; custom ones go beyond `category` and `tag`.

register_post_type('portfolio', [...]);
register_taxonomy('project_type', 'portfolio', [...]);

### 6. **What are hooks? Types?**
**Answer**:
– **Hooks** let you modify WordPress behavior without editing core.
– **Types**:
– **Action**: Executes custom code at specific events (`add_action`)
– **Filter**: Alters data before it's used (`add_filter`)

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### 7. **What are template hierarchy levels in WordPress?**
**Answer**:
Hierarchy determines what template file is used.
Example:

single-product.php → single.php → singular.php → index.php

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### 8. **What is the difference between `get_template_part()` and `include()`?**
**Answer**:
– `get_template_part()` allows child themes to override template parts.
– `include()` is a direct PHP inclusion without fallback support.

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### 9. **How do you enqueue scripts and styles correctly in WordPress?**
**Answer**:

function theme_scripts() {
  wp_enqueue_style('main-style', get_stylesheet_uri());
  wp_enqueue_script('main-js', get_template_directory_uri() . '/js/main.js', ['jquery'], null, true);
}
add_action('wp_enqueue_scripts', 'theme_scripts');

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## 🔵 ADVANCED LEVEL

### 10. **What’s the difference between `admin-ajax.php` and the REST API?**
**Answer**:
– `admin-ajax.php` is legacy; often slower, uses admin context.
– **REST API** is modern, cleaner, supports JSON, and works better with JS frontends like React/Vue.

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### 11. **How do you secure a WordPress site?**
**Answer**:
– Limit login attempts
– Use HTTPS
– Update core/themes/plugins regularly
– Sanitize and validate inputs
– Use `NONCE` for form security
– Restrict file editing via `wp-config.php`

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### 12. **How do you create a Gutenberg block?**
**Answer**:
1. Register block in `block.json`
2. Use `@wordpress/scripts` or `@wordpress/create-block`
3. Define block functionality in JS + CSS
4. Optionally register server-side render via `render_callback`

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### 13. **How would you optimize performance in WordPress?**
**Answer**:
– Use caching (object, page, browser)
– Optimize images
– Minify assets
– Avoid heavy plugins
– Use a CDN
– Lazy load content
– Query optimization using `transients` or custom SQL when needed

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### 14. **Explain the use of `WP_Query`, `query_posts()` and `get_posts()`**
**Answer**:
– `WP_Query`: Most flexible, creates a custom loop.
– `get_posts()`: Simpler version of `WP_Query` with limited args, returns array.
– `query_posts()`: Modifies the main query (not recommended).

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### 15. **How do you create a multisite in WordPress?**
**Answer**:
– Enable multisite in `wp-config.php`:

define('WP_ALLOW_MULTISITE', true);

– Setup via admin panel under Tools → Network Setup

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## 🟥 SYSTEM + ARCHITECTURE + DESIGN

### 16. **How do you structure a large-scale WordPress plugin?**
**Answer**:
– Use **OOP structure**
– Modularize (Controller, Models, Views)
– PSR-4 Autoloading
– Use **Service Providers** for dependency management
– Singleton pattern for plugin class

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### 17. **How do you handle background tasks in WordPress?**
**Answer**:
– `wp_cron`
– Custom WP CLI commands for manual runs
– `Action Scheduler` library for background processing (used by WooCommerce)

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### 18. **Explain `transients` and `options` APIs**
**Answer**:
– **Options API**: Stores persistent config data.
– **Transients API**: Caches data with expiration (stored in DB or memory if using object cache).

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## 🎯 COMMON SENIOR DEVELOPER QUESTIONS

### 19. **Have you used Composer in WordPress?**
**Answer**: Yes, I’ve used Composer to manage dependencies in WordPress custom plugins/themes or Bedrock-based projects, enabling better dependency control.

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### 20. **What is your approach to debugging complex issues in WordPress?**
**Answer**:
– Enable WP_DEBUG and log errors
– Use Query Monitor
– Log database queries
– Check server logs, plugin conflicts
– Use `xdebug` or similar for step-by-step inspection

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Would you like:
– A **PDF cheat sheet** of these questions?
– Or mock **interview sessions** / live coding tasks?

Let me know and I’ll prepare the next step.