How to create an array containing 1…N numbers in JavaScript ?
Last Updated :
26 Dec, 2023
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:
We can use a 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: In this example, we are using for Loop
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);
|
Output
[
1, 2, 3, 4, 5,
6, 7, 8, 9, 10,
11, 12
]
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: In this example, we are using Spread Operator.
Javascript
function createArray(N) {
return [...Array(N).keys()].map(i => i + 1);
}
let N = 12;
let arr = createArray(N);
console.log(arr);
|
Output
[
1, 2, 3, 4, 5,
6, 7, 8, 9, 10,
11, 12
]
We can also use the Array.from() method to create an array containing numbers from 1 to N.
Example: In this example, we are using from() Method
Javascript
function createArray(N) {
return Array.from({length: N}, (_, index) => index + 1);
}
let N = 12;
let arr = createArray(N);
console.log(arr);
|
Output
[
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: In this example, we are third-party library.
Javascript
const _ = require( "lodash" );
let range_arr = _.range(1,5);
console.log(range_arr);
|
Output:
[ 1, 2, 3, 4 ]
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