JavaScript: how to create a range of integers

In this article we will see how to create a range of integers with JavaScript.

We can implement the following function:

'use strict';

function createNumberRange(start = 1, end = 10) {
     return Array.from({ length: end - start + 1 }, (_, i) => start + i);
}

The createNumberRange function takes two parameters: start and end. These parameters respectively represent the start value and the end value for the range of numbers to be generated.

Within the function, the method Array.from() is used . This method creates a new array from an iterable object or an array-like object. In our case, the iterable object is an object created using the syntax { length: end - start + 1 }. This object has a length property which indicates the length of the array we wish to create. The length is calculated by subtracting the value of start from the value of end and adding 1.

So let's move on to another part of the code: (_, i) => start + i. This is an arrow function which is used as an optional argument of the Array.from() method. The underscore _ represents a parameter that will not be used in the function body. The i parameter represents the index of the array generated by Array.from().

Inside the body of the arrow function, it is calculated the value of each element of the returned array. This is done by adding the value of start to index i.

Finally, the createNumberRange function returns the array of numbers generated using Array.from().