CODEWITHSUNDEEP
javascriptvariables
KMcA
KMcA

Reputation: 1213

Declaring a variable in Javascript - Constructor vs Literal

Watching a tutorial today I came across the following:

var q2Var1 = "hi there.",
    q2Var2 = String( "another string here." );

Is q2Var the "constructor notation" and q2Var the "literal notation" for declaring a variable, or am I not drawing the correct conclusion?

Thank you.

Upvotes: 1

Views: 100

Answers (2)

Guffa
Guffa

Reputation: 700910

No, neither of those use a constructor to create a string object.

The first is just a string primitive, the second is a string primitive that is sent through the String conversion function, which will just return the string primitive unchanged.

The String conversion function is usually used to turn other things into string primitives, for example a number:

var s = String(42);

To create a String object you use the new keyword:

var s = new String("hi there.");

The String object has all the methods that you are used to use on a string, like the length property. The reason that you can use them on string primitives also, is that they are automatically converted to String objects when you use a method on them.

So, this:

var l = "asdf".length;

actually does the same as:

var l = new String("asdf").length;

The String conversion function always returns a string primitive, so if you have a String object, the function will turn it back into a string primitive:

var s = "asdf"; // typeof s returns "string"

var s = new String(s); // typeof s now returns "object"

s = String(s); // typeof s now returns "string"

Upvotes: 3

foaly
foaly

Reputation: 352

I never heard those names before, but 'constructor notation' would most likely be the q2Var2 one, since you're passing arguments to the constructor of String. It's not really important how you call them though, is it? :P

Upvotes: 0

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