What does const do in JavaScript?
A). Declares a block-scoped variable
B). Declares a constant value
C). Declares a global variable
D). Declares a function
What will be the output of let { a, b } = { a: 1, b: 2, c: 3 };?
A). a is 1, b is 2
B). a is 2, b is 3
C). a is 1, b is undefined
D). a is 3, b is undefined
Can a constant objects properties be changed?
A). Yes
B). No
C). Only if redeclared
D). Only with special methods
What will const x = { a: 1 }; x.a = 2; do?
A). Throw an error
B). Change x.a to 2
C). Change x to 2
D). Do nothing
How to use destructuring to extract properties from an object?
A). { a, b } = { a: 1, b: 2 }
B). let { a, b } = { a: 1, b: 2 };
C). let a, b = { a: 1, b: 2 };
D). let (a, b) = { a: 1, b: 2 };
Which of these correctly assigns values to variables using array destructuring?
A). [x, y, z] = [1, 2, 3]
B). [1, 2, 3] = [x, y, z]
C). let [x y z] = [1 2 3];
D). (x, y, z) = [1, 2, 3];
What is the outcome of let x = 8; x %= 3;?
A). 1
B). 2
C). 3
D). 5
Which assignment will fail?
A). const x = 10; x = 20;
B). let y = 5; y = 10;
C). var z = 15; z = 30;
D). let a = { b: 2 }; a.b = 3;
What will let x = 5, y = 10; [x, y] = [y, x]; do?
A). Nothing
B). Throws an error
C). Swaps values of x and y
D). None of the above
How do you assign default values in destructuring?
A). let { a, b } = { a: 1 };
B). let { a = 1, b = 2 } = {};
C). let [a, b] = [1, 2];
D). let { a, b } = { a: 1, b: 2 };