Q31 What is the output of this code if the HTML contains an element with id demo and text 'Hello'?
document.getElementById('demo').textContent = 'Hi'; console.log(document.getElementById('demo').textContent);

Q32 What will be the result of the following code if the HTML has multiple p tags?
let paragraphs = document.getElementsByTagName('p');
for(let i = 0; i < paragraphs.length; i++) {
paragraphs[i].style.color = 'blue';
}

Q33 Identify the error in this code:
document.getElementByld('demo').innerText = 'Welcome';

Q34 What is an event in the context of JavaScript?

Q35 What is event bubbling in JavaScript?

Q36 How can you stop event propagation in JavaScript?

Q37 Consider the following code snippet:
element.addEventListener('click', function() {
console.log('Element clicked');
});
What does this code do?

Q38 Identify the error in this code:
document.getElementById('myBtn').onClick = function() {
console.log('Button clicked');
};

Q39 What does AJAX stand for in web development?

Q40 What is the purpose of the Fetch API in JavaScript?

Q41 $$\begin{gathered} What does the following JavaScript code do? \\ fetch(\text{'}https://api.example.com/data\text{'}) \\ .then(response => response.json(\left)\right) \\ .then(data => console.log(data\left)\right); \end{gathered}$$

Q42 $$\begin{gathered} How does this code handle errors when using the Fetch API? \\ fetch(\text{'}https://api.example.com/data\text{'}) \\ .then(response => \{ \\ if (!response.ok) \{ \\ throw new Error(\text{'}Network response was not ok\text{'}); \\ \} \\ return response.json\left(\right); \\ \left\}\right) \\ .catch(error => console.error(\text{'}Fetch error:\text{'}, error\left)\right); \end{gathered}$$

Q43 $$\begin{gathered} Identify the issue in this fetch request: \\ fetch(\text{'}https://api.example.com/data\text{'}, \{ \\ method: \text{'}GET\text{'}, \\ body: JSON.stringify\left(\right\{id: 1\left\}\right) \\ \left\}\right); \end{gathered}$$

Q44 $$\begin{gathered} Spot the error in this code: \\ fetch(\text{'}https://api.example.com/data\text{'}) \\ .then(response => console.log(response.json\left(\right)\left)\right); \end{gathered}$$

Q45 What is the purpose of the try...catch statement in JavaScript?

Q46 What type of error is thrown when an undefined variable is used in JavaScript?

Q47 Which statement is used to manually throw an exception in JavaScript?

Q48 What is the difference between a SyntaxError and a ReferenceError in JavaScript?

Q49 Identify the error in this code:
try {
let result = 'Result';
console.log(result);
} catch(e) {
console.log(e);
} finally {
console.log(reslt);
}

Q50 $$\begin{gathered} What is the problem with this code? \\ try \{ // code \} catch\left(e\right) \{ console.log(e); \} \end{gathered}$$

Q51 What ES6 feature allows us to combine multiple strings and variables?

Q52 What is the purpose of the let and const keywords in ES6?

Q53 How does the spread operator (...) work in ES6?

Q54 Consider the following ES6 code:
const square = x => x * x; console.log(square(4));
What is the output?

Q55 Find the mistake in this ES6 code:
let obj = { a: 1, b: 2, a: 3 }; console.log(obj.a);

Q56 How can "Callback Hell" be avoided in JavaScript?

Q57 $$\begin{gathered} Consider this code: \\ function firstFunction(params, callback) \{ \\ // Do something, then callback() \\ \} \\ function secondFunction\left(params\right) \{ \\ firstFunction(params, function(err, data) \{ \\ if (err) \{ \\ console.log(\text{'}Error:\text{'}, err); \\ \} else \{ \\ console.log(\text{'}Data:\text{'}, data); \\ \} \\ \}); \} \\ What pattern does this represent? \end{gathered}$$

Q58 Spot the error in this callback usage:
function fetchData(callback) {
if (error) {
callback(error);
} return callback(null, data);
}

Q59 What happens if a promise is rejected and there is no .catch() block?

Q60 What does the following code do?
new Promise((resolve, reject) => {
setTimeout(() => resolve('Result'), 2000);
})
.then(result => console.log(result));