new Array("John", "Bob", "Sue"); // condensed array

["John", "Bob", "Sue"]; // literal array

var array = new Array(10);

var array = [];
array.length = 10;

String.prototype.repeat= function(n){
    n= n || 1;
    return Array(n+1).join(this);
}

document.writeln('/'.repeat(80))

> a = [3,,,,5,2,3]
3,,,,5,2,3
> a = new Array(3,,,,5,2,3)
SyntaxError: Unexpected token ,

a = new Array(10)
,,,,,,,,,
a = new Array(1,2,30)
1,2,30