Published: October 02 2021

Vanilla JS - Create an array with a range of numbers in a JavaScript

This tutorial includes some quick examples of how to generate a range of numbers (e.g. [0, 1, 2, ..., N]) in an array in JavaScript.

The below examples include creating an array with ten numbers from zero to nine ([0, 1, 2, ..., 9]), an array with the range one to ten ([1, 2, 3, ..., 10]), an array with the range five to twenty ([5, 6, 7, ..., 20]), and an array with the range zero to one hundred with a step size of ten ([0, 10, 20, ..., 100]).

Here they are in action: (See on StackBlitz at https://stackblitz.com/edit/vanilla-js-create-array-with-range-of-numbers)


JavaScript Create Range Example Code

The code snippets use the following Vanilla JS tools to create a range of numbers in an array:

  • the Array() function creates a new javascript array with a specified number of empty slots (e.g. Array(10) creates the array [empty x 10]).
  • the Array.keys() method returns a new iterator object with the key/index of each slot in an array (e.g. 0, 1, 2, ..., N).
  • the ES6 Spread Operator (...) expands/converts the keys iterator object into a list of elements that can be passed to a literal Array constructor ([elem1, elem2, ..., elemN]).
  • the Array.map() function is used to create a new array with a modified range of numbers.
  • the Math.floor() function rounds a number down to the nearest integer, it's used in the last example to ensure a whole number is passed to the Array() function regardless of the step size.
(function() {
    // 0 to 9
    const range = [...Array(10).keys()];
    document.getElementById('rangeOne').innerHTML = JSON.stringify(range);
})();

(function() {
    // 1 to 10
    const start = 1;
    const end = 10;
    const range = [...Array(end - start + 1).keys()].map(x => x + start);
    document.getElementById('rangeTwo').innerHTML = JSON.stringify(range);
})();

(function() {
    // 5 to 20
    const start = 5;
    const end = 20;
    const range = [...Array(end - start + 1).keys()].map(x => x + start);
    document.getElementById('rangeThree').innerHTML = JSON.stringify(range);
})();

(function() {
    // 0 to 100 step 10
    const start = 0;
    const end = 100;
    const step = 10;
    const arrayLength = Math.floor(((end - start) / step)) + 1;
    const range = [...Array(arrayLength).keys()].map(x => (x * step) + start);
    document.getElementById('rangeFour').innerHTML = JSON.stringify(range);
})();


More info on JavaScript functions used

For more info on the Vanilla JS functions and operator used in the example see the below links:

 


Subscribe or Follow Me For Updates

Subscribe to my YouTube channel or follow me on Twitter, Facebook or GitHub to be notified when I post new content.

Other than coding...

I'm currently attempting to travel around Australia by motorcycle with my wife Tina on a pair of Royal Enfield Himalayans. You can follow our adventures on YouTube, Instagram and Facebook.


Need Some Vanilla JS Help?

Search fiverr to find help quickly from experienced Vanilla JS developers.



Supported by