💻 PHP Full Stack Interview Guide

A1. HTML stands for HyperText Markup Language. It is a markup language used to create and structure web pages using elements and tags.

A2. Basic HTML structure includes:

A3. HTML tags are the markup code (like <p>), while HTML elements include both the opening tag, content, and closing tag (like <p>Hello</p>).

A4. HTML attributes provide additional information about elements.

Examples:

• id="header"
• class="menu"
• src="image.jpg"
• href="link.html"

A5.

• Block-level elements (div, p, h1) take full width and start on new lines
• Inline elements (span, a, img) take only necessary width and don't break lines

A6. DOCTYPE tells the browser which version of HTML the page uses, ensuring proper rendering and standards compliance.

A7. Tables use <table>, <tr>, <td> tags. Colspan spans columns horizontally, rowspan spans rows vertically.

A8. Forms collect user input using <form> tag.

Input types: text, password, email, number, checkbox, radio, file, submit, reset.

A9.

A10.

• Images: <img src="image.jpg" loading="lazy" alt="description">
• Videos: <video controls><source src="video.mp4" type="video/mp4"></video>

A11. Semantic elements clearly describe meaning:

• <header>
• <nav>
• <main>
• <article>
• <section>
• <aside>
• <footer>

A12.

• Ordered lists: <ol><li>Item</li></ol>
• Unordered lists: <ul><li>Item</li></ul>
• Definition lists: <dl><dt>Term</dt><dd>Definition</dd></dl>

A13. HTML entities represent special characters:

• &lt; (<)
• &gt; (>)
• &amp; (&)
• &quot; (")
• &nbsp; (space)

A14. Iframes embed another document within current page:

Used for: embedding maps, videos, external content.

A15. Meta tags provide metadata about HTML documents: charset, viewport, description, keywords. Important for SEO and responsive design.

A16. CSS (Cascading Style Sheets) styles HTML elements.

Advantages:

• Separation of content and presentation
• Reusability
• Faster loading
• Easier maintenance

A17.

1. Inline CSS: style="color:red"
2. Internal CSS: <style> in head
3. External CSS: separate .css file linked via <link>

A18.

• Tag selector: p{}
• ID selector: #header{}
• Class selector: .menu{}
• Universal selector: *{}
• Descendant: div p{}

A19. Box model includes: Content, Padding (inner space), Border, Margin (outer space).

Total width = content + padding + border + margin

A20.

A21.

• Pseudo-classes style element states: :hover, :focus, :nth-child()
• Pseudo-elements style parts: ::before, ::after, ::first-line

A22. Specificity determines which CSS rule applies:

• Inline (1000) > IDs (100) > Classes (10) > Elements (1)
• Higher specificity wins

A23. Flexbox provides efficient layout for containers.

Properties:

• display: flex
• justify-content
• align-items
• flex-direction
• flex-wrap

A24. Float removes element from normal flow, floating left/right. Clear prevents elements from floating beside specified sides.

A25. Media queries apply styles based on device characteristics:

A26.

• Horizontal: margin: 0 auto (block), text-align: center (inline)
• Vertical: flexbox, grid, or position with transform

A27.

• Margin: space outside element border (affects other elements)
• Padding: space inside element border (affects element size)

A28.

• Inheritance: child elements inherit parent styles
• Cascade: multiple rules combine based on specificity, importance, and source order

A29.

• Transitions: smooth changes between states
• Animations: complex movements with keyframes
• Both enhance user experience

A30. Use:

• Flexible grids
• Media queries
• Flexible images (max-width: 100%)
• Viewport meta tag
• Relative units (%, em, rem)

A31. Bootstrap is a CSS framework for responsive web development.

Advantages:

• Pre-built components
• Responsive grid system
• Faster development
• Cross-browser compatibility

A32. 12-column grid with containers, rows, and columns.

Classes: col-xs-*, col-sm-*, col-md-*, col-lg-* for different screen sizes.

A33.

A34. Use navbar classes:

• navbar
• navbar-nav
• navbar-toggler for mobile menu
• collapse for collapsible content

A35. Text utilities:

• .text-primary
• .text-success
• .text-muted
• .text-center
• .text-uppercase
• .lead for emphasis

A36. Pre-built UI elements:

• Alerts
• Buttons
• Cards
• Dropdowns
• Forms
• Modals
• Navbar
• Pagination
• Progress bars

A37.

• Override CSS with custom stylesheets
• Use Sass variables
• Customize through Bootstrap's build tools
• Use CSS custom properties

A38. Design starts with mobile screens, then scales up. Bootstrap uses min-width media queries, defaulting to mobile styles.

A39.

• Button styles: .btn-primary, .btn-secondary, .btn-success, .btn-danger
• Sizes: .btn-lg, .btn-sm
• States: .active, .disabled

A40. Use:

• .form-group for grouping
• .form-control for inputs
• .form-check for checkboxes/radios
• Validation classes for feedback

A41. JavaScript is a dynamic programming language for web development.

Features:

• Interpreted
• Object-oriented
• Event-driven
• Loosely typed
• Client/server-side execution

A42.

• Primitive: Number, String, Boolean, Undefined, Null, Symbol, BigInt
• Non-primitive: Object (including arrays, functions)

A43. Hoisting moves variable and function declarations to the top of their scope. Variables are hoisted but not initialized; functions are fully hoisted.

A44.

A45. Closure is when inner function has access to outer function's variables even after outer function returns. Creates private variables and data encapsulation.

A46. Events are actions (click, load, change). Event handling responds to events using event listeners:

A47.

A48. Arrays store multiple values.

Methods: push(), pop(), shift(), unshift(), slice(), splice(), map(), filter(), forEach().

A49. Functions are reusable code blocks.

Declarations:

• Function declaration
• Function expression
• Arrow functions
• Anonymous functions

A50. DOM (Document Object Model) represents HTML as objects.

Manipulation: getElementById(), querySelector(), innerHTML, textContent, setAttribute().

A51. 'this' refers to the object context where function is called. Value depends on how function is invoked: method, function, constructor, or arrow function.

A52.

• Promises: handle asynchronous operations with resolve/reject
• Async/await: provides synchronous-like syntax for promises, making code more readable

A53. Common methods:

• length
• indexOf()
• slice()
• substring()
• replace()
• split()
• toUpperCase()
• toLowerCase()
• trim()

A54. Scope determines variable accessibility.

Types:

• Global scope (everywhere)
• Function scope (within function)
• Block scope (within {})

A55. Use try-catch-finally blocks:

• try: code that might fail
• catch: handle errors
• finally: always executes
• Throw custom errors with 'throw'

A56. jQuery is a JavaScript library that simplifies DOM manipulation, events, and AJAX.

Advantages:

• Shorter code
• Cross-browser compatibility
• Powerful selectors

A57. Basic syntax: $(selector).action()

Examples:

• $('#id')
• $('.class')
• $('element')
• $(this)

A58.

A59. Similar to CSS selectors:

• $('#id') (ID)
• $('.class') (class)
• $('tag') (element)
• $(':first') (pseudo-selectors)

A60. Events handle user interactions:

• click()
• hover()
• focus()
• blur()
• change()
• submit()
• keyup()
• mouseenter()

A61.

Effects: hide(), show(), toggle(), fadeIn(), fadeOut(), slideUp(), slideDown()

Custom animations: animate()

A62. Methods:

• html()
• text()
• val()
• attr()
• css()
• addClass()
• removeClass()
• append()
• prepend()
• remove()

A63. Chaining allows multiple methods on same element:

A64. AJAX methods:

• $.ajax()
• $.get()
• $.post()
• $.load()

Handle asynchronous requests without page refresh.

A65. Plugins extend jQuery functionality.

Usage: include plugin file, initialize with options:

A66. AJAX (Asynchronous JavaScript and XML) updates web pages without full reload.

Advantages:

• Better user experience
• Faster
• Reduced server load

A67. XMLHttpRequest enables AJAX requests.

Properties: readyState, status, responseText

Methods: open(), send(), setRequestHeader()

A68.

State 4 with status 200 indicates successful completion.

A69. Use onreadystatechange event handler to check readyState and status, then process responseText or responseXML.

A70.

A71. PHP (PHP: Hypertext Preprocessor) is server-side scripting language.

Features:

• Open-source
• Platform-independent
• Database support
• Dynamic typing

A72. Variables start with $ sign:

PHP is loosely typed, no need to declare data type.

A73.

• Scalar: boolean, integer, float, string
• Compound: array, object, callable, iterable
• Special: resource, NULL

A74.

A75.

• Arithmetic: +, -, *, /
• Comparison: ==, ===, !=
• Logical: &&, ||, !
• Assignment: =, +=
• Increment: ++, --

A76.

• Conditional: if, else, elseif, switch
• Loops: for, while, do-while, foreach
• Alternative syntax with colons and endstatements

A77. Arrays store multiple values.

Types:

• Indexed arrays (numeric keys)
• Associative arrays (string keys)
• Multidimensional arrays

A78. Functions are reusable code blocks:

Built-in functions available for strings, arrays, dates.

A79.

A80. Use $_FILES superglobal, check file properties (size, type, error), use move_uploaded_file() to save uploaded files.

A81.

• Include: includes file, continues on failure
• Require: includes file, stops on failure
• _once variants: prevent multiple inclusions

A82.

• Error types: Parse, Fatal, Warning, Notice
• Handle with try-catch blocks
• error_reporting()
• Custom error handlers

A83. Built-in arrays:

• $_GET
• $_POST
• $_SESSION
• $_COOKIE
• $_FILES
• $_SERVER
• $_ENV
• $GLOBALS

Available in all scopes.

A84. Use MySQLi or PDO:

Check connection, execute queries, handle results.

A85. Prepared statements prevent SQL injection, improve performance. Use placeholders:

A86. Common functions:

• strlen()
• substr()
• str_replace()
• explode()
• implode()
• trim()
• strtolower()
• strtoupper()

A87. Object-Oriented Programming with classes, objects.

Principles:

• Encapsulation
• Inheritance
• Polymorphism
• Abstraction

A88. Validate server-side:

• Check required fields
• Data types
• Formats
• Use filter_var()
• Regular expressions
• Custom validation functions

A89. Namespaces organize code, avoid naming conflicts:

Use with use statements or full qualified names.

A90. Automatically loads classes when needed:

Or Composer's autoloader. Improves performance and organization.

A91. MySQL is open-source relational database.

Features:

• ACID compliance
• Multi-user access
• SQL standard compliance
• Replication
• Partitioning

A92.

• Numeric: INT, DECIMAL, FLOAT
• String: VARCHAR, TEXT, CHAR
• Date: DATE, TIME, DATETIME, TIMESTAMP
• Binary: BLOB

A93.

A94. Indexes speed up queries.

Types:

• PRIMARY (unique identifier)
• INDEX/KEY (faster searches)
• UNIQUE (unique values)
• FULLTEXT (text search)

A95. Joins combine tables:

A96. Transactions group operations.

ACID:

• Atomicity (all or nothing)
• Consistency (valid state)
• Isolation (concurrent safety)
• Durability (permanent)

A97. Rules for data integrity:

• NOT NULL
• UNIQUE
• PRIMARY KEY
• FOREIGN KEY
• CHECK
• DEFAULT

Enforce data validity.

A98.

• Use indexes
• EXPLAIN query execution
• Avoid SELECT *
• Use appropriate data types
• Optimize WHERE clauses
• Normalize database

A99. Process to reduce redundancy.

Forms:

• 1NF (atomic values)
• 2NF (partial dependency)
• 3NF (transitive dependency)
• BCNF

A100.

Backup methods:

• mysqldump (logical)
• Binary backup (physical)
• Replication

Recovery: restore from backup, point-in-time recovery, binary logs.