Functional Programming in JavaScript

Let point be an object { x: 0, y: 0 }. What is the result of { x: 1, ...point }?

• { x: 0, y: 0 }

• { x: 0, y: 1 }

• { x: 1, y: 0 }

• { x: 1, y : 1 }

What is the output of the console.log?

• { x: 0, y: 0 }

• [ 0, 0 ]

• undefined

• [Function: getPoint]

What will happen if the following code is executed?

• A SyntaxError will be raised in the first line.

• A SyntaxError will be raised in the second line.

• The console.log will output [] (i.e. the empty array)

• The console.log will output [Function (anonymous)]

What does { ...obj1, ...obj2 } do (assuming that obj1 and obj2 are objects)?

• Creates a new object containing obj1 and obj2 as properties.

• Creates a new object containing the keys of obj1 and obj2 as properties.

• Creates a new object containing keys of obj1 and obj2 as properties unless obj1 or obj2 have equal keys.

• Copies obj2 into obj1.

Which of these statements about the filter method is true?

• It retrieves all of the elements that meet a certain predicate

• The returned elements are deep copied

• The returned elements are shallow copied

• It only works for primitive values

What does the expression Object.entries({ x: 0, y: 0 }).map(([x1, x2]) => [x1, x2]) return?

• { x: 0, y: 0 }

• [ [ 'x', 0 ], [ 'y', 0 ] ]

• Nothing, a SyntaxError will happen

• [ 0, 0 ]

Which of these statements are true about pure functions?

• They have no side effects

• They are easily testable

• They don't mutate global state

• Their output(s) depends only on their input(s)