Table of contents
- Array Basic operations
- 1. Find the first item in the array
- 2. Find the last item in the array
- 3. Addition of array values
- 4. Arrange in descending order
- 5. Arrange in ascending order
- 6. Push item to array
- 7. remove item from array
- 8. push item from beginning of an array
- 9. remove the item from the beginning of an array
- 10. slice array from index 3
- 10. slice array in the range
- 11. Updated 3rd item with 0 in array
- 12. Convert to comma separated values
- 13. Convert to comma separated using array method
- 14. Convert array to _ separated string
- 15. update index 3 with value 4
- 16. Merge two arrays
- 17. find max value from an array
- 18. find min value from an array
- 19. find index of a given number in array
- 20. find lastIndex of a given number in the array
- 21. verify every element is greater than -1
- 22. verify at least one element greater than 1
- 23. Fill last two elements with number 1
- 24. Filter elements > 2
- 25. reverse array in place
- 26. remove falsy values from an array
- 27. Multiply every item with 2
- 28. Remove duplicates from an array
- 29. capture only integers from an array
- 30. capture chunks of an array.
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]]