Javascript - php - oop

In js: What will be the result of: "true && false" ?

• true

• false

• undefined

• null

Answer explanation

In the logical AND operator (&&), both operands must be true for the result to be true. Since one operand (false) is false, the result is false.

In js: What does 'new Date().getFullYear()' return?

• Current month

• Current year

• Current day

• Current time

Answer explanation

getFullYear() returns the current year

In js: Which method is used to remove the last element from an array?

• pop()

• shift()

• slice()

• push()

Answer explanation

The pop() method removes the last element from an array and returns that element.

In js: Which loop runs at least once, even if the condition is false?

• for loop

• while loop

• do..while loop

• forEach loop

Answer explanation

In a do...while loop, the code block is executed once before the condition is tested.

in js: How do you access the value of a property named 'age' in an object person?

• person{age}

• person.getAge()

• person.age

• person->a

Answer explanation

Dot notation (person.age) is used to access properties in an object.

What is the main purpose of closures in JavaScript?

• To execute asynchronous code

• To handle errors

• To store private data

• To manipulate the DOM

Answer explanation

Closures allow a function to access and remember its lexical scope even when it's executed outside that scope.

Which keyword is used for throwing an error in JavaScript?

• catch

• throw

• try

• error

Answer explanation

The throw keyword is used to throw custom errors or exceptions in JavaScript.

Which data type is JSON?

• String

• Object

• Number

• Array

Answer explanation

JSON (JavaScript Object Notation) is a string representation of JavaScript objects.

Which method is used to add a new element to the end of a DOM tree?

• appendChild()

• createElement()

• removeElement()

• removeChild()

Answer explanation

The appendChild() method adds a new child node to the end of the list of children of a specified parent node.

Which method is used to attach an event handler to an element in JavaScript?

• addEventListener()

• attachEvent()

• onClick()

• handleEvent()

Answer explanation

addEventListener() is the preferred method to attach event listeners as it allows attaching multiple event handlers to a single element.