30 Asked Interview Questions and Answers (2024)

Ques 26. What is a closure in the context of JavaScript's event handling?

In the context of event handling, a closure allows a function to retain access to variables in its lexical scope even after the outer function has finished executing. This is often used to maintain state across multiple event callbacks.

Example:

```javascript
function createCounter() {
  let count = 0;
  return function() {
    console.log(count++);
  };
}

const counter = createCounter();
counter(); // Outputs: 0
counter(); // Outputs: 1
```

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Ques 27. What is the difference between 'inline' and 'block' elements in CSS?

'inline' elements only take up as much width as necessary and do not start on a new line. 'block' elements take up the full width available and start on a new line.

Example:

```css
/* Inline element example */
span {
  display: inline;
}

/* Block element example */
div {
  display: block;
}```

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Ques 28. Explain the purpose of the 'box-sizing' property in CSS.

The 'box-sizing' property determines how the total width and height of an element are calculated. 'content-box' includes only the content, while 'border-box' includes padding and border in the calculation.

Example:

```css
/* Using box-sizing: border-box */
div {
  box-sizing: border-box;
  width: 200px;
  padding: 10px;
  border: 5px solid #000;
}```

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Ques 29. What is the purpose of the 'data-' attribute in HTML?

The 'data-' attribute is used to store custom data private to the page or application. It provides a way to attach additional information to HTML elements without using non-standard attributes.

Example:

```html
This is a custom element.

```

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Frontend Developer Interview Questions and Answers

Ques 26. What is a closure in the context of JavaScript's event handling?

Ques 27. What is the difference between 'inline' and 'block' elements in CSS?

Ques 28. Explain the purpose of the 'box-sizing' property in CSS.

Ques 29. What is the purpose of the 'data-' attribute in HTML?

Ques 30. What is the difference between 'throttling' and 'debouncing' in JavaScript?

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