### Check if all values in an array are equal

You can check it using `every`

method on the array:

1const areEqual = arr => {2 return arr.length > 0 && arr.every(item => item === arr[0]);3}4// areEqual([11, 32, 21, 54]) === false 🚫5// areEqual(['blue', 'blue', 'blue']) === true ✅

### Convert an array of strings value to numbers

JS provides different ways to convert a string value into a number, but the best one is to use `Number`

object in a non-constructor context (without the new keyword). It also takes care of the decimals as well:

1const toNumbers = arr => arr.map(Number);2// toNumbers(["2", "3", "4"]) returns [2, 3, 4]

### Create an array of cumulative sum

To get the summation of a sequence of numbers in an array, we can use currying to access the previous value:

1const accumulate = arr => {2 return arr.map((sum => value => sum += value)(0));3}45/*6accumulate([1, 2, 3, 4]) === [1, 3, 6, 10]7// 1 = 18// 1 + 2 = 39// 1 + 2 + 3 = 610// 1 + 2 + 3 + 4 = 1011*/

### Create an array of numbers in the given range

To create an array that contains all numbers between `starting index`

and `ending index`

, including `starting index`

and `ending index`

themselves:

1const range = (min, max) => {2 return Array(max - min + 1).fill(0).map((_, i) => max - min + i)3};4// range(5, 10) === [5, 6, 7, 8, 9, 10]

### Empty an array

JS provides various ways of clearing existing array:

1const empty = arr => arr.length = 0;23// Or using splice but since the .splice() function will return an array4// with all the removed items, it will actually return a copy of5// the original array6const empty = arr => arr.splice(0, arr.length)78// Or9arr = [];

### Find the maximum or minimum item of an array

1const max = arr => Math.max(...arr);2const min = arr => Math.min(...arr);

### Check if an object is an array

1const isArray = obj => Array.isArray(obj);

### Get a random item from an array

1const randomItem = arr => {2 return arr[Math.floor(Math.random() * arr.length)]3};

### Get the average of an array

1const average = arr => {2 return arr.reduce((a, b) => a + b, 0) / arr.length;3}

### Get the sum of array of numbers

1const sum = arr => arr.reduce((a, b) => a + b, 0);

### Get the unique values of an array

1const unique = arr => [...new Set(arr)];23// Or4const unique = arr => {5 return arr.filter((el, i, array) => array.indexOf(el) === i);6}

### Merge two arrays

We can achieve this in different ways:

1// 1 - To just merge the arrays (without removing duplicates)2const merge = (a, b) => a.concat(b);3// OR4const merge = (a, b) => [...a, ...b];56// 2 - To merge the arrays and removing duplicates7const merge = [...new Set(a.concat(b))];8// OR9const merge = [...new Set([...a, ...b])];

I hope this blog would have piqued your interest in knowing more about these helper methods. Go ahead, try them out and share with others.

Cheers !