What is array literal notation in javascript and when should you use it?

Question

JSLint is giving me this error:

Problem at line 11 character 33: Use the array literal notation [].

var myArray = new Array(); 

What is array literal notation and why does it want me to use it instead?

It shows here that new Array(); should work fine... is there something I'm missing?

Answer 1

array literal notation is where you define a new array using just empty brackets. In your example:

var myArray = []; 

It is the "new" way of defining arrays, and I suppose it is shorter/cleaner.

The examples below explain the difference between them:

var a = [],            // these are the same     b = new Array(),   // a and b are arrays with length 0      c = ['foo', 'bar'],           // these are the same     d = new Array('foo', 'bar'),  // c and d are arrays with 2 strings      // these are different:     e = [3],             // e.length == 1, e[0] == 3     f = new Array(3);   // f.length == 3, f[0] == undefined 

Reference: What’s the difference between “Array()” and “[]” while declaring a JavaScript array?

Answer 2

See also: What’s wrong with var x = new Array();

Aside from the Crockford argument, I believe it is also due to the fact that other languages have similar data structures that happen to use the same syntax; for example, Python has lists and dictionaries; see the following examples:

// this is a Python list a = [66.25, 333, 333, 1, 1234.5]  // this is a Python dictionary tel = {'jack': 4098, 'sape': 4139} 

Isn't it neat how Python is also grammatically correct Javascript? (yes, the ending semi-colons are missing, but those aren't required for Javascript, either)

Thus, by reusing common paradigms in programming, we save everyone from having to relearn something that shouldn't have to.