Question

In JavaScript, from my understanding, the below are all same:

var carter2 = new String();
var carter2 = '';
var carter2 = "";

Which one is the most preferred?

Answer 1

Don’t use

var str = new String();

Because

var str = new String("dog");
var str2 = new String("dog"); 
str == str2; // false

But

var str = "dog";
var str2 = "dog"; 
str == str2; // true

However, because of type coercion, the following works (Thanks to Rocket for pointing it out)

var str = new String("dog");
var str2 = "dog"; 
str == str2; // true

Single and double quotes don’t matter, except for what quotes need to be escaped. Many others have noted that single quotes are better when creating HTML strings, since XHTML expects attributes to have double quotes, and you won’t need to escape them.