What is the difference between Array() and [] in Javascript and why would I use one over the other?

Answer 1

I believe they're identical. I never use new Array();

Answer 2

new Array(2) proudces an array of size 2, containing two undefineds. [2] produces an array of size 1, containing number 2. new Array IMO doesn't fit with the spirit of JavaScript, even though it may make array construction much more findable. That may or may not be of any importance (I use literals almost exclusively in JavaScript for all applicable types, and I've authored/maintained large pieces of JavaScript [30-50 KLOC] successfully).

edit I guess the reasons seasoned javascript programmers avoid new Array syntax are:

• it doesn't behave uniformly across argument numbers and types ((new Array(X)).length == 1 for any X as long as typeof(X) != "number"
• it's more verbose and the only thing you gain is the irregularity

Answer 3

Another (minor) reason to use [] in preference to new Array() is that Array could potentially be overridden (though I've never seen it happen) and [] is guaranteed to work.

Array = "something";
var a = new Array(); // Fails
var b = []; // Works