5.5 Array Declaration
Arrays are initialized by enclosing comma , separated values in brackets []. A plain [] represents the empty array, whereas [1, 2, 3] initializes an array with three elements 1, 2 and 3.
The generated code may be less concise on platforms that do not support array initialization. Essentially, such initialization code then looks like this:
var a = new Array();
a.push(1);
a.push(2);
a.push(3);
This should be considered when deciding if a function should be inlined as it may inline more code than visible in the syntax.
Advanced initialization techniques are described in Array Comprehension.