Since the Array constructor is ambiguous in how it deals with its parameters,
it is highly recommended to always use the array literals - [] notation -
when creating new arrays.
[1, 2, 3]; // Result: [1, 2, 3]
new Array(1, 2, 3); // Result: [1, 2, 3]
[3]; // Result: [3]
new Array(3); // Result: []
new Array('3') // Result: ['3']
In cases when there is only one argument passed to the Array constructor
and when that argument is a Number, the constructor will return a new sparse
array with the length property set to the value of the argument. It should be
noted that only the length property of the new array will be set this way;
the actual indexes of the array will not be initialized.
var arr = new Array(3);
arr[1]; // undefined
1 in arr; // false, the index was not set
The behavior of being able to set the length of the array upfront only comes in
handy in a few cases, like repeating a string, in which it avoids the use of a
for loop code.
new Array(count + 1).join(stringToRepeat);
The use of the Array constructor should be avoided as much as possible.
Literals are definitely preferred. They are shorter and have a clearer syntax;
therefore, they also increase the readability of the code.