array-literal-vs-condensed.md

What is the difference between an array literal vs a condensed array?

Sometimes a trick question, but if they asked it they are probably fishing for something.

First off, what does this all mean?

Array literal

An array literal is our usual way of declaring and array.

var a = [1, 2, 3] // a = [1, 2, 3]

Condensed array

A condensed array is instatiated using the Array constructor.

var b = new Array(1, 2, 3) // b = [1, 2, 3]

No Difference?

So in this case there is no difference. We've used both of them nicely and ended up with the same result. However the condensed array approach has a few other intricacies.

Consider the following...

var c = new Array(10) // c = [ , , , , , , , , , ]

This can save some time if you want to create an arry with multiple undefined values.

But it's not all good news.

Consider the following...

var d = [4, 5, , 7, 8] // d = [4, 5, undefined, 7, 8]

var e = new Array(4, 5, , 7, 8 ) // Syntax error

So, there is a difference depending on how you use it.