var x = new Array（）;怎么了？

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

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 2

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 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.