Some X array utility functions in JS

const array = [1,2,3,4,5];

Array Basic operations

1. Find the first item in the array

console.log(array[0]);

1

2. Find the last item in the array

console.log(array[array.length - 1]);

5

3. Addition of array values

console.log(array.reduce((previousValue, currentValue) => previousValue += currentValue, 0));

15

4. Arrange in descending order

console.log(array.sort((a,b) => b-a));

[5,4,3,2,1]

5. Arrange in ascending order

console.log(array.sort((a, b) => a-b));

[1,2,3,4,5]

6. Push item to array

array.push(6);

console.log(array);

[1,2,3,4,5,6]

7. remove item from array

array.pop();

console.log(array);

[1,2,3,4,5]

8. push item from beginning of an array

array.unshift(0);

console.log(array);

[0,1,2,3,4,5]

9. remove the item from the beginning of an array

array.shift();

console.log(array);

[1,2,3,4,5]

10. slice array from index 3

console.log(array.slice(3));

[4]

10. slice array in the range

console.log(array.slice(3, 4));

[4]

11. Updated 3rd item with 0 in array

array.splice(3, 1, 0);

console.log(array);

[1,2,3,0,5]

12. Convert to comma separated values

console.log(array.toString());

'1,2,3,0,5'

13. Convert to comma separated using array method

console.log(array.join());

'1,2,3,0,5'

14. Convert array to _ separated string

console.log(array.join('_'));

'1_2_3_0_5'

15. update index 3 with value 4

array[2] = 4;

console.log(array);

[1,2,3,4,5]

16. Merge two arrays

const newArr = [6,7,8,9];

console.log(array.concat(newArr));

[1,2,3,4,5,6,7,8,9]

17. find max value from an array

console.log(Math.max(...array));

9

18. find min value from an array

console.log(Math.min(...array));

1

19. find index of a given number in array

console.log(array.indexOf(4));

3

20. find lastIndex of a given number in the array

console.log(array.lastIndexOf(4));

3

21. verify every element is greater than -1

console.log(array.every(item => item > -1));

true

22. verify at least one element greater than 1

console.log(array.some(item => item > 1));

true

23. Fill last two elements with number 1

console.log(array.fill(1, 5));

[1,2,3,4,5,1,1,1,1]

24. Filter elements > 2

console.log(array.filter(item => item > 2));

[3,4,5]

25. reverse array in place

console.log(array.reverse());

[1,1,1,1,5,4,3,2,1]

26. remove falsy values from an array

array.push(false, null, 0, undefined); console.log(array);

[1,2,3,4,5,1,1,1,1,false, null, 0, undefined]

console.log(array.filter(Boolean));

[1,2,3,4,5,1,1,1,1]

27. Multiply every item with 2

console.log(array.map(item => item = item * 2));

[2,4,6,10,2,2,2,2]

28. Remove duplicates from an array

console.log(...new Set(array));

[1,2,3,4,5]

29. capture only integers from an array

array.push(1.23, 2.34); console.log(array);

[1,2,3,4,5,1,1,1,1,1.23,2.34]

console.log(array.filter(item => Number.isInteger(item)));

[1,2,3,4,5,1,1,1,1]

30. capture chunks of an array.

const firstArray  = [1,2,3,4,5];
const chunks = [];
for (let i = 0; i<firstArray.length;i+=2) {
    chunks.push(firstArray.slice(i, i+2));
}
console.log(chunks);
> [[1,2][3,4][5]]