What is the purpose of the 'typeof' operator in JavaScript?
A). To check if a variable is defined
B). To check the data type of a variable
C). To assign a data type to a variable
D). To increment the value of a variable
Which statement correctly declares a JavaScript arrow function?
A). const add = (a, => a + b;
B). function add(a, { return a + b; }
C). const add = function(a, { return a + b; }
D). let add = function(a, { return a + b; };
How can you add a new element to the end of a JavaScript array?
A). colors.push('blue');
B). colors.add('blue');
C). colors.insert('blue', colors.length);
D). colors[colors.length] = 'blue';
What is the purpose of the 'this' keyword in JavaScript?
A). To refer to the current HTML element
B). To refer to the current JavaScript file
C). To refer to the current object
D). To refer to the current function
How can you prevent a JavaScript function from executing immediately?
A). Using async/await
B). Using the defer attribute in HTML script tag
C). Wrapping the function in parentheses
D). Using the setTimeout function
What is the purpose of the 'break' statement in a JavaScript switch case?
A). To continue to the next case
B). To exit the switch statement
C). To restart the switch statement
D). To execute the default case
How can you convert a string to a number in JavaScript?
A). parseInt('10')
B). parseFloat('10.5')
C). Number('10')
D). All of the above
How do you concatenate strings in JavaScript?
A). Using the + operator
B). Using the - operator
C). Using the * operator
D). Using the / operator
Which method is used to remove the last element from a JavaScript array?
A). colors.pop();
B). colors.removeLast();
C). colors.splice(-1, 1);
D). colors.deleteLast();
What is the correct way to declare a JavaScript class?
A). class Rectangle {}
B). let Rectangle = {}
C). function Rectangle() {}
D). Rectangle {}