Generating random indexes

When you want to generate random indexes to use on an array, make sure you use Math.floor instead of Math.round or your randomness could suffer.

Some novice programmers might generate a random index like this:

Math.round(Math.random() * LENGTH_OF_ARRAY);

But using Math.round has some issues. What you actually want to use is Math.floor:

Math.floor(Math.random() * LENGTH_OF_ARRAY);

You can run the experiment yourself here: http://ift.tt/2wIfxh7