# How to get a random value from a JavaScript array

07 Feb ยท by Tim Kamanin ยท 2 min readRecently I had a task: create a function that picks a random color from the list of colors.

Here's an array of colors:

```
const colors = [
'#FFFFFF',
'#F06B4F',
'#F2AE52',
'#B0CD6D',
'#A33120'
];
```

Now let's write a `randomColor`

function that randomly picks a color from the list:

```
function randomColor(colors) {
return colors[Math.floor(Math.random() * colors.length)];
}
```

Of course, we can use this function to pick any random value from an array, not only colors.

We could stop here and call it a day, but let's take a look at the `randomColor`

and see what it does, bit by bit.

`Math.floor(Math.random() * colors.length)`

generates a random index for the`colors`

array;`Math.floor`

function returns the largest integer for a given number;`Math.random`

function returns us a random number in the range of 0 - 1;`Math.random() * colors.length`

, we get a random number between 0 - 1, let's say 0.5 and normalize it, multiplying it by the length of the array (so we don't get the index larger that our array's length);`Math.floor(Math.random() * colors.length)`

, gives us a random integer (array index) by rounding-down our normalized value to the nearest integer. Notice, we don't do`Math.ceil`

to round the number up, because if we get something like`0.99 x 5 = 4.95`

, it'd be rounded up to`5`

which gives us index larger than the length of the array. Thus, we always round down that number:`Math.floor(4.95) = 4`

, i.e. last element of the array;`colors[Math.floor(Math.random() * colors.length)]`

returns us an element of the array at the random index, just like we wanted.

The final code looks like:

```
const colors = [
'#FFFFFF',
'#F06B4F',
'#F2AE52',
'#B0CD6D',
'#A33120'
];
function randomColor(colors) {
return colors[Math.floor(Math.random() * colors.length)];
}
randomColor(colors); // #B0CD6D ;)
```