Updating reference examples in utilities/ to ES6 syntax

[stalgiag]

I think this was missed when resolving #3382

The reference examples in the files in src/utilities still need to be updated to ES6 syntax.

The todo here is mostly to change var to let or const in the reference examples inside the folder linked above. There are tons of resources online for learning about ES6. Here is an interactive guide that covers the biggest features.

[hsab]

Is this referring to 0.9 in particular? Because I remember updating those for the #3874

[shubymao]

@stalgiag I would like to try and help later today. Does all the examples in utilities need to be updated?

[stalgiag]

Apologies! I was just looking at my local copy and the website when I posted this. I didn't realize that you were fixing the examples as well but that makes sense. Closing now!