What's wrong with var x = new Array();

Question

In JSLint, it warns that

var x = new Array();

(That's not a real variable name) should be

var result = [];

What is wrong with the 1st syntax? What's the reasoning behind the suggestion?

Answer 1

Crockford doesn't like new. Therefore, JSLint expects you to avoid it when possible. And creating a new array object is possible without using new....

Answer 2

It's safer to use [] than it is to use new Array(), because you can actually override the value of Array in JavaScript:

Array = function() { };

var x = new Array();
// x is now an Object instead of an Array.

In other words, [] is unambiguous.

Answer 3

It seems like you can get different performance based on which you are using and for what purpose depending on browser or environment:

http://jsperf.com/new-array-vs-literal/11 ( [1,.2] vs new Array(1,.2) ) the literal is way faster in this circumstance.

http://jsperf.com/new-array-vs-literal/7 ( new Array(500000) vs [].length(500000) ) new Array is faster in chrome v21 it seems for this test by about 7% or 30%) depending on what you do.

Answer 4

Nothing wrong with either form, but you usually see literals used wherever possible-

var s='' is not more correct than var s=new String()....

Answer 5

There's nothing wrong with the first syntax per se. In fact, on w3schools, it lists new Array() as the way to create an array. The problem is that this is the "old way." The "new way", [] is shorter, and allows you to initialize values in the array, as in ["foo", "bar"]. Most developers prefer [] to new Array() in terms of good style.