Deep copy duplicates both values and memory addresses, creating a new independent object. Shallow copy only copies the reference address, sharing memory with the original object, so changes to the original affect the copy.

For shallow copies:

• Direct assignment (=)
• Spread operator (...)
• Object.assign()

For deep copies:

• JSON.stringify() followed by JSON.parse()
• Object.create()

Note: Object.assign() performs deep copy for primitive values but shallow copy for object references.

Semantic HTML tags improve code readability by clearly indicating content structure.

ES6 introduced key features:

• let and const for block-scoped variables
• Destructuring assignment
• Template literals for string interpolation
• Spread operator for array/object manipulation
• Arrow functions
• Classes
• Promises for asynchronous operations
• Set and Map collections
• Symbol for unique property keys

Event bubbling propagates events from child to parent elements. Cancel with:

element.onclick = function(event) {
    event = event || window.event;
    event.cancelBubble = true;
}

CSS box model:

• Padding: space between element content and border
• Margin: space between elements

Vue conditional rendering:

• v-if: Toggles DOM element existence
• v-show: Toggles CSS display property

CSS units:

• px: Fixed pixels
• em: Relative to parent font-size
• rem: Relative to root element font-size
• vw/vh: Viewport width/height percentages

Webpack configuration example:

const path = require('path');

module.exports = {
    entry: './src/main.js',
    output: {
        path: path.resolve(__dirname, 'dist'),
        filename: 'bundle.js'
    },
    module: {
        rules: [
            { test: /\.vue$/, use: 'vue-loader' }
        ]
    },
    plugins: []
};

JavaScript event loop processes synchronous tasks first, then asynchronous tasks from microtask and macrotask queues.

Vue Router implements client-side routing using hash mode or HTML5 History API.

CSS selector specificity (highest to lowest):

1. Inline styles
2. ID selectors
3. Class/pseudo-class selectors
4. Element/pseudo-element selectors

Flexbox layout properties: Container:

• justify-content: Horizontal alignment
• align-items: Vertical alignment
• flex-direction: Main axis direction
• flex-wrap: Wrapping behavior

Items:

• order: Display order
• flex-grow: Growth factor
• flex-shrink: Shrink factor
• flex-basis: Initial size

Cookies store session data in browsers, primarily for authentication.

Vue lifecycle hooks:

• created: After instance creation, before DOM mounting
• mounted: After DOM is mounted created executes before mounted.

Web storage:

• localStorage: Persistent storage
• sessionStorage: Session-only storage
• Cookies: Small data with expiration

HTTP status codes:

• 2xx: Success
• 3xx: Redirection
• 4xx: Client errors
• 5xx: Server errors

Array deduplication methods:

• Set constructor
• Array.prototype.indexOf()
• Array.prototype.includes()

Mobile responsive techniques:

• Viewport meta tag
• Media queries
• Flexible units (vw, vh, rem, %)

Position elements at bottom:

• Absolute/fixed positioning with bottom: 0
• Previous element with 100vh height

JavaScript prototype chain enables inheritance through prototype objects.

Routers operate at the network layer in OSI model.

Bubble sort time complexity: O(n²)

Virtual DOM optimizes updates by comparing JavaScript object representations before applying minimal DOM changes.

Vue component data must be a function to prevent shared state across instances.

DOM selection:

• querySelector(): First matching element
• querySelectorAll(): NodeList of all matches

Function parameter passing:

• Primitives: By value
• Objects: By reference

Array type checking:

• Array.isArray()
• instanceof Array

CSS triangle:

.triangle {
    width: 0;
    height: 0;
    border-left: 50px solid transparent;
    border-right: 50px solid transparent;
    border-bottom: 100px solid #000;
}

Text alignment:

• Single line: text-align: center
• Multiple lines: text-align: left

Element hiding:

• display: none: Removes from layout
• visibility: hidden: Hides but preserves space

Array iteration:

• forEach(): Executes callback, returns undefined
• map(): Returns new transformed array

Vue template abbreviations:

• v-on: @
• v-bind: :
• v-slot: #