WorksheetsJavaScript Arrays Quiz
Total questions: 30
Worksheet time: 15mins
What is the output?
let arr = [10, 20, 30];
console.log(arr[1]);
20
10
30
undefined
What is printed?
let fruits = ["apple", "banana"];
fruits.push("cherry");
console.log(fruits);
["apple", "banana", "cherry"]
["cherry", "banana", "apple"]
["apple", "banana"]
Error
Output?
let arr = [1, 2, 3];
arr.pop();
console.log(arr);
[1, 2]
[2, 3]
[1, 2, 3, 4]
Error
Find the output:
let arr = ["red", "green", "blue"];
arr.shift();
console.log(arr);
["green", "blue"]
["red", "green"]
["blue", "red"]
Error
Output of the following:
let nums = [5, 10, 15];
console.log(nums.length);
3
2
5
undefined
Result?
let a = [1, 2, 3];
a.unshift(0);
console.log(a);
[0, 1, 2, 3]
[1, 2, 3, 0]
[1, 2, 3]
[0]
What is printed?
let arr = [1, 2, 3, 4];
console.log(arr.indexOf(3));
2
3
1
-1
Output?
let colors = ["red", "green", "blue"];
console.log(colors.includes("yellow"));
false
true
undefined
Error
Output:
let arr = [2, 4, 6];
arr[1] = 10;
console.log(arr);
[2, 10, 6]
[10, 4, 6]
[2, 4, 10]
Error
Output of:
let arr = [1, 2, 3];
console.log(arr.reverse());
[3, 2, 1]
[1, 2, 3]
Error
undefined
Output?
let arr = [2, 4, 6];
let newArr = arr.map(x => x * 2);
console.log(newArr);
[4, 8, 12]
[2, 4, 6, 8]
[x * 2]
Error
What will this code log?
let arr = [5, 10, 15];
let result = arr.filter(x => x > 8);
console.log(result);
[10, 15]
[5]
[]
undefined
Find the output:
let arr = [3, 6, 9];
let sum = arr.reduce((a, b) => a + b, 0);
console.log(sum);
18
9
0
undefined
Output?
let arr = [10, 20, 30];
let sliced = arr.slice(1);
console.log(sliced);
[20, 30]
[10, 20]
[10]
[30]
What’s printed?
let arr = [4, 2, 8, 6];
arr.sort();
console.log(arr);
[2, 4, 6, 8]
[8, 6, 4, 2]
[4, 2, 8, 6]
["2", "4", "6", "8"]
What is output?
let arr = ["a", "b", "c"];
arr.splice(1, 1, "x");
console.log(arr);
["a", "x", "c"]
["x", "b", "c"]
["a", "b"]
["a", "b", "x"]
Result?
let arr = [1, 2, 3];
let doubled = [];
arr.forEach(x => doubled.push(x * 2));
console.log(doubled);
[2, 4, 6]
[1, 2, 3]
Error
undefined
Output?
let arr = [2, 4, 6];
let even = arr.every(x => x % 2 === 0);
console.log(even);
true
false
undefined
Error
Output:
let arr = ["A", "B", "C"];
let joined = arr.join("-");
console.log(joined);
"A-B-C"
["A-B-C"]
["A", "B", "C"]
Error
What will be the output?
let a = [1, 2];
let b = [3, 4];
console.log(a.concat(b));
[1, 2, 3, 4]
[3, 4, 1, 2]
[[1, 2], [3, 4]]
Error
Output?
let arr = [1, , 3];
console.log(arr.length);
3
2
1
undefined
Output?
let arr = [1, 2];
let copy = arr;
copy.push(3);
console.log(arr);
[1, 2, 3]
[1, 2]
[3]
Error
Output?
let arr = [1, 2, 3];
console.log([...arr, 4, 5]);
[1, 2, 3, 4, 5]
[4, 5, 1, 2, 3]
[[1, 2, 3], 4, 5]
Error
Output?
let arr = [1, 2, 3];
arr.length = 1;
console.log(arr);
[1]
[1, 2, 3]
[]
undefined
Output?
let arr = [2, 4, 6];
delete arr[1];
console.log(arr);
[2, empty, 6]
[2, 6]
[2, undefined, 6]
Error
Output?
let arr = [10, 20, 30];
console.log(arr.find(x => x > 15));
20
10
undefined
Error
What will this print?
let arr = [1, 2, 3];
console.log(arr.reduce((a, b) => a * b));
6
9
5
Error
Output?
let arr = [4, 9, 16];
let sqrt = arr.map(Math.sqrt);
console.log(sqrt);
[2, 3, 4]
[8, 27, 64]
[9, 81, 256]
Error
What happens?
let arr = [1, 2, 3];
arr = [];
console.log(arr);
[]
[1, 2, 3]
undefined
Error
Output?
console.log([1, 2] == [1, 2]);
false
true
undefined
Error
