Create an array sequence from 1 to N in a single line in JavaScript

This post will discuss how to create an array sequence from 1 to N in JavaScript.

There are several ways to create an array sequence of integers from 1 (inclusive) to N (inclusive), where the value N is dynamic.

1. Using `Array.from()` function

const N = 5;

const arr = Array.from({length: N}, (_, index) => index + 1);

console.log(arr);

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

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Or use Array Constructor

const N = 5;

const arr = Array.from(Array(N), (_, index) => index + 1);

console.log(arr);

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

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const N = 5;

const arr = Array.from(Array(N+1).keys()).slice(1);

console.log(arr);

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

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2. Using Spread operator

const N = 5;

const arr = [...Array(N+1).keys()].slice(1);

console.log(arr);

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

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const N = 5;

const arr = [...Array(N).keys()].map(x => ++x);

console.log(arr);

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

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const N = 5;

const arr = [...Array(N)].map((_, index) => index + 1);

console.log(arr);

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

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3. Using Underscore Library

var _ = require('underscore');

const N = 5;

const arr = _.range(1, N+1);

console.log(arr);

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

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The _.range method is overloaded to generate a range from start (inclusive) to stop (exclusive), incremented (or decremented) by step.

var _ = require('underscore');

const start = 1, end = 10, step = 2;

const arr = _.range(start, end, step);

console.log(arr);

Output: [ 1, 3, 5, 7, 9 ]

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That’s all about creating an array sequence from 1 to N in a single line in JavaScript.

Create an array sequence from 1 to N in a single line in JavaScript

1. Using Array.from() function

2. Using Spread operator

3. Using Underscore Library

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1. Using `Array.from()` function