Initialize an array with range 0 to N in JavaScript

This post will discuss how to initialize an array with a range from 0 to N in JavaScript.

There are several ways to create a numbered integer array from 0 (inclusive) to N (exclusive), incremented by step 1, where the value N is dynamic.

1. Using ES6 Spread operator

var n = 5;

var arr = [...Array(n).keys()];

console.log(arr);

Output: [ 0, 1, 2, 3, 4 ]

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2. Using Underscore `range()` method

var _ = require('underscore');

var n = 5;

var arr = _.range(n);

console.log(arr);

Output: [ 0, 1, 2, 3, 4 ]

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3. Using `Array.from()` function

var n = 5;

var arr = Array.from({length: n}, (item, index) => index);

console.log(arr);

Output: [ 0, 1, 2, 3, 4 ]

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Alternatively, using Array.from() with Array.prototype.keys() method in ES6.

var n = 5;

var arr = Array.from(Array(n).keys());

console.log(arr);

Output: [ 0, 1, 2, 3, 4 ]

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4. Using `Array.prototype.map()` function

var n = 5;

var arr = [...Array(n)].map((item, index) => index);

console.log(arr);

Output: [ 0, 1, 2, 3, 4 ]

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5. Using `Function.prototype.apply()` function

var n = 5;

var arr = Array.apply(null, {length: n}).map(Number.call, Number);

console.log(arr);

Output: [ 0, 1, 2, 3, 4 ]

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6. Using array literal notation

var n = 5;

var arr = [];

for (var i = 0; i < n; i++) {

arr.push(i);

}

console.log(arr);

Output: [ 0, 1, 2, 3, 4 ]

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7. Using Array Constructor

var n = 5;

var arr = new Array(n);

for (var i = 0; i < n; i++) {

arr[i] = i;

}

console.log(arr);

Output: [ 0, 1, 2, 3, 4 ]

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That’s all about initializing an array with a range of 0 to N in JavaScript.

Initialize an array with range 0 to N in JavaScript

1. Using ES6 Spread operator

2. Using Underscore range() method

3. Using Array.from() function

4. Using Array.prototype.map() function

5. Using Function.prototype.apply() function

6. Using array literal notation

7. Using Array Constructor

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2. Using Underscore `range()` method

3. Using `Array.from()` function

4. Using `Array.prototype.map()` function

5. Using `Function.prototype.apply()` function