Which statement correctly declares a JavaScript object?
A). let person = {name: 'John', age: 30};
B). const person = ('name' => 'John', 'age' => 30);
C). const person = ['name', 'John', 'age', 30];
D). var person = {name: 'John', age: 30};
How do you access the last element of a JavaScript array?
A). colors[colors.length - 1];
B). colors.last();
C). colors[-1];
D). colors.getLast();
What is the purpose of the 'constructor' method in a JavaScript class?
A). To create new instances of the class
B). To initialize class properties
C). To define class methods
D). To define class inheritance
What is the purpose of the 'return' statement in a JavaScript function?
A). To end the function execution
B). To return a value from the function
C). To print a value to the console
D). To declare a variable
How do you concatenate strings in JavaScript?
A). Using the + operator
B). Using the - operator
C). Using the * operator
D). Using the / operator
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
Which operator is used for strict inequality in JavaScript?
A). !==
B). !=
C). <>
D). /=
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
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';
How can you comment a single line of code in JavaScript?
A). // This is a comment
B). <!-- This is a comment -->
C). /* This is a comment */
D). ''' This is a comment '''