gistfile1.js

var array = [];
console.log("my array has " + array.length + " elements and it looks like: ", array);
console.log("WTF?");
array[5] = 1;    
console.log("now my array has " + array.length + " elements and it looks like: ", array);
console.log("Okey...");
/*    
results from Chrome-Safari console:

my array has 0 elements and it looks like:  [undefined, undefined, undefined, undefined, undefined, 1]
WTF?
now my array has 6 elements and it looks like:  [undefined, undefined, undefined, undefined, undefined, 1]
Okey...
*/