This is an alternative way to deliver a string version of an array. In this case, it is formatted as an Array literal and can then be used in an eval() function to assign another array. It means that Arrays can be deep copied more easily.
If you run the example, it should yield something like this:
["one", 2, "III"]
This is quite different to the result of a toString() method which would yield this for the same array contents:
The result of this method is a String primitive version of the array formatted as an Array literal.
// Create an array and display its source myObject = new Array("one", 2, "III"); document.write(myObject.toSource());