For a change of pace, this assessment does not require you to write code. Instead you will need to read some code and answer questions about it. It is a closed book assessment and you should keep your eyes on your own screen and not talk with your neighbors while you take it. You do not need to submit a pull request this time; your answers are saved automatically when you select from a multiple choice answer or hit enter on a free-form answer.
When this code runs, does it call the foo function?
let x = 10;
if (x % 2 === 0) {
foo();
}Yes
No
When this code runs, which functions are called?
let x = 37;
if (x < 37) {
foo(x);
} else {
bar(x);
}Just foo
Just bar
Both foo and bar
Neither foo nor bar.
When this code runs, which functions are called?
let x = 37;
if (x * -1 < 37) {
foo(x);
}
bar(x);Just foo
Just bar
Both foo and bar
Neither foo nor bar.
In this code:
let x = 0;
for (let i = 0; i < 10; i++) {
x = x + i * 10;
}what part is the “condition” of the for loop.
let x = 0
let i = 0
i < 10
i++
x = x + i * 10
Given this definition:
const N = 100;How many times does the body of this loop execute?
for (let i = 0; i < N; i++) {
// code here
}99
100
101
To fully understand this code you should know that Math.random() is a function that returns a random number between 0 and 1. With that in mind, after this code runs:
let randomNumbers = [];
for (let i = 0; i < 10; i++) {
randomNumbers.push(Math.random());
}What does the following expression evaluate to?
randomNumbers.lengthWe can’t know, it’s random.
It’s random but definitely at least 10.
It’s random but definitely less than 10.
It’s random but definitely a multiple of 10.
10
Less than 10
How many times is the foo function called when this code runs:
for (let i = 0; i < 5; i++) {
for (let j = 0; j < 4; j++) {
foo(i, j);
}
}4
30
5
20
12
Given this code:
let c = 0;
for (let i = 0; i < 4; i++) {
for (let j = 0; j < i; j++) {
c++;
}
}what is the value of c after the loop finishes?
4
3
6
10
Given this code:
let x = 0;
for (let i = 0; i < 10; i++) {
x = x + i;
}What is the best description of the value of x after the loop has completed?
The sum of the numbers from 0 to 10
The sum of the numbers from 0 to 9
The number of elements in the array x
11
What is the best description of when this loop will stop?
let done = false;
while (!done) {
const r = Math.random();
done = r < 0.01;
}Never, it’s an infinite loop
Immediately, the loop body never executes
When Math.random() returns a number less that 0.01
When Math.random() returns a number greater than 0.01
When done is less than 0.01
In the following code, assume isPrime is a function that says whether the number it is passed is a prime number.
const foo = (limit, max) => {
let primes = 0;
for (let n = 0; n < max; n++) {
if (isPrime(n)) {
primes++;
}
if (primes > limit) {
return true;
}
}
return false;
}Which of the following best describes what this function does?
It tests whether limit is a prime number.
It tests whether there are at most max prime numbers below limit.
It tests whether there are more than limit prime numbers below max.
It tests whether limit and max are both prime numbers.
Given this code:
const xs = [10, 11, 71];What does the following expression evaluate to?
xs[0]10
71
3
11
0
Given this code:
const xs = [10, 11, 71];Which of the following expressions evaluate to 71?
xs[-1]
xs[xs.length]
xs[xs.length + 1]
xs[xs.length - 1]
What does the following expression evaluate to?
[4, 5, 6].length0
6
4
3
2
What does the following expression evaluate to?
[ ].length0
Nothing, it’s a syntax error.
undefined
Given this array:
const xs = [
['foo', 'bar', 'baz'],
['quux'],
['fred', 'barney', 'wilma', 'betty']
];which of the following expressions evaluates to 'barney'?
xs[2]
xs[5]
xs[2][1]
xs[1][2]
After this code executes what is the value of the first element of xs?
const xs = [10, 20, 30];
xs[0] = xs[2] * 1010
100
3
200
300
Nothing, this code won’t run because xs was declared with const.
Given the following definition:
const foo = [10, 20, false]What does this expression evaluate to:
(foo[0] * foo[1]) < 200 === foo[2]true
false
Assuming numbers is an array of numbers and given this code:
let x = 0;
for (let i = 0; i < numbers.length; i++) {
x = x + numbers[i];
}What is the best description of the value of x after the loop has completed?
The sum of the numbers from 0 to numbers.length - 1.
The sum of the numbers from 0 to numbers.length.
The sum of the elements of the array.
The sum of all but the last number in the array.
The sum of the even numbers in numbers.
What does this function do:
const foo = (words) => {
let result = [];
for (let i = 0; i < words.length; i++) {
result.push(words[i].toUpperCase());
}
return result;
}Changes all the words in the words array to uppercase.
Produces a new array containing the words in words that are all uppercase.
Produces a new array containing all the words in words in uppercase.
Consider this function:
const foo = (xs) => {
let result = [];
for (let i = 0; i < xs.length; i++) {
result.push(xs[xs.length - i]);
}
return result;
}For up to 5 points, describe what it does:
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