Get a random item from a JavaScript array.

Get a random int

First we need to get a random number that is an int and isn’t too large. We can extract this into a small helper:

const getRandomInt = max => Math.floor(Math.random() * max)

Explanation:

Math.floor()

Returns the largest integer less than or equal to a given number.

Math.random()

Returns a pseudo-random number between 0 and 1, usually not an integer, but it can be 0, but never 1. in the range 0 to less than 1 (inclusive of 0, but not 1).

Or in a fancier way, with min and max arguments:

const getRandomInt = (max, min = 0) => {
  min = Math.ceil(min)
  max = Math.floor(max)
 
  return Math.floor(Math.random() * (max - min + 1)) + min
}

Get the random array item

Then use bracket notation to access the array at the random index provided by the helper function:

const arr = ['foo', 'bar', 'baz', 'quix', 'fooz']
 
const randomItem = arr[getRandomInt(arr.length)]

How random is that random int generator?

I wrote a post about it, where I’m visualizing that random data.

To be precise, it’s about this random: