Literals and Objects - When to use what?

Question

I wonder when to use literals and when to use objects to create data type values.

Eg.

When do I use these:

/regexp/
"string"

and when these:

new RegExp("regexp")
new String("string")

Will these give me the same methods and properties?

Answer 1

new RegExp() can be useful when you want to concatenate a value stored in a variable.

var x = "exp";
var regex = new RegExp("reg" + x);

I don't know of any reason not to use String literals, though.

An example of where you may get an unexpected result using a constructor is when creating an Array.

var arr = new Array( 3 ); // creates an Array with an initial length of 3

var arr = new Array( "3" ); // creates an Array with an initial length of
                            //    1 item that has the value "3"

Overall, I think you'd be safe sticking to literals.