Frontend Developer Interview Questions and Answers

Ques 7. Explain the purpose of the 'rem' unit in CSS and how it differs from 'em'.

'rem' (root em) is relative to the font-size of the root element, while 'em' is relative to the font-size of the nearest parent element with a font-size. 'rem' is not affected by the parent element's font-size.

Example:

```css
html {
  font-size: 16px;
}

body {
  font-size: 1.5rem; /* 24px */
}
```

Ques 8. Explain the difference between 'cookie', 'sessionStorage', and 'localStorage'.

'cookie' is a small piece of data stored on the client's computer, 'sessionStorage' stores data for the duration of a page session, and 'localStorage' persists data even after the browser is closed.

Ques 9. Explain the concept of 'event bubbling' in JavaScript.

'Event bubbling' is the process where the event starts from the target element and bubbles up the DOM hierarchy until it reaches the root. It allows for delegating event handling to a common ancestor.

Ques 10. What is the purpose of the 'transition' property in CSS?

The 'transition' property in CSS is used to create smooth transitions between property values over a specified duration. It is commonly used for animations and effects.

Example:

```css
/* Example of using transition */
.element {
  transition: width 0.5s ease-in-out;
}
```

Ques 11. What is the role of the 'viewport' meta tag in HTML?

The 'viewport' meta tag in HTML is used to control the layout viewport of the browser, ensuring that the webpage is displayed correctly on various devices by setting the initial scale, width, and zoom level.

Example:

```html

```