Question

var v = new Array('Bill','Erik','Pam');
v.toString();
v.constructor;

In Firebug 1.7.3, FF 5.0.1

v.constructor //Returns "undefined, not Array();

also:

 var s = new String('Couch Potato');


    s.indexOf('Couch');
    s.slice(1,5);
    s.split(" ");
    s.join(' ');  //FF returns "s.join" is not a function.

Why is this?

Answer 1

For the constructor property, apparently firebug has a bug. try alerting that value (alert([].constructor)) and you’ll see that it is not undefined.
The join method is an array method and it’s normal for firebug to show an error when calling it on a string. In javascript, the String is not an array of char like in other languages (probably you got confused).
The only way you can call the join method in your case would be after you transformed your string into an array : "abcd".split('').join('').