In this article, we will see how to create an array containing 1. . . N numbers using JavaScript. We can create an array by using different methods.
There are some methods to create an array containing 1…N numbers, which are given below:
- Using for Loop
- Using Spread Operator
- Using from() Method
- Using Lodash _.range() Method
Method 1: Using for Loop
We can use for loop to create an array containing numbers from 1 to N in JavaScript. The for loop iterates from 1 to N and pushes each number to an array.
Example:
Javascript
function createArray(N) { let newArr = []; for (let i = 1; i <= N; i++) { newArr.push(i); } return newArr;}let N = 12;let arr = createArray(N);console.log(arr); |
[ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ]
Method 2: Using Spread Operator
We can also use Spread Operator to create an array containing 1…N numbers. We use Array() constructor to create a new array of length N, and then use keys() method to get an iterator over the indices of the array. Then spread the iterator into an array using the spread operator (…) and map each element of the resulting array to its corresponding index value plus 1.
Example:
Javascript
function createArray(N) { return [...Array(N).keys()].map(i => i + 1);}let N = 12;let arr = createArray(N);console.log(arr); |
[ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ]
Method 3: Using from() Method
We can also use the Array.from() method to create an array containing numbers from 1 to N.
Example:
Javascript
function createArray(N) { return Array.from({length: N}, (_, index) => index + 1);}let N = 12;let arr = createArray(N);console.log(arr); |
[ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ]
Method 4: Using third-party library
The _.range() method is used to create an array of numbers progressing from the given start value up to, but not including the end value.
For installing `lodash`, run the following command
npm init -y
npm install lodash
Example:
Javascript
// Requiring the lodash libraryconst _ = require("lodash");// Using the _.range() methodlet range_arr = _.range(1,5);// Printing the outputconsole.log(range_arr); |
Output:
[ 1, 2, 3, 4 ]
