Web Developer Questions et reponses d'entretien
Question 1. Explain the concept of 'Immutable Data' in JavaScript.
Immutable data cannot be changed once created, promoting safer state management and reducing bugs in applications.
Example:
const array = [1, 2, 3];
const newArray = [...array, 4];
Question 2. What is the 'event.preventDefault()' method in JavaScript used for?
'event.preventDefault()' is used to prevent the default behavior associated with an event, such as preventing a form submission or a link from navigating.
Example:
document.getElementById('myForm').addEventListener('submit', function(event) {
event.preventDefault();
// additional handling code
});
Question 3. Explain the purpose of the 'SQL JOIN' operation in database queries.
The 'SQL JOIN' operation combines rows from two or more tables based on a related column, allowing the retrieval of data from multiple tables in a single query.
Example:
SELECT users.username, orders.order_id FROM users
JOIN orders ON users.user_id = orders.user_id;
Question 4. What is the purpose of the 'transition' property in CSS?
The 'transition' property is used to create smooth transitions between different property values, allowing for animation effects.
Example:
div {
transition: width 2s, height 2s;
}
Question 5. Explain the concept of 'Debouncing' in JavaScript.
Debouncing is a technique used to ensure that time-consuming tasks do not fire so often, making it more efficient for tasks like handling input events.
Example:
function debounce(func, delay) {
let timeoutId;
return function() {
clearTimeout(timeoutId);
timeoutId = setTimeout(() => func.apply(this, arguments), delay);
};
}
Les plus utiles selon les utilisateurs :