Usage of toString in JavaScript [duplicate]

Answer 1

level is a variable (and thus an object).

1 is a literal. They are not objects and the interpreter thinks about them completely differently.

http://www.cs.brown.edu/courses/bridge/1998/res/javascript/javascript-tutorial.html#4

Answer 2

You need 1..toString or (1).toString to get the number literal

Answer 3

It's just a language grammar limitation.

Since 1. is a legal literal number (and 1.t is not) the tokeniser will split this into the following tokens:

1.
toString
(
)

And that's an illegal sequence of tokens. It's object method, instead of object . method.

In the working versions in @Joey's answer, the braces prevent the tokenizer from treating the dot as part of the number literal instead of as a separate token, as does writing:

1.0.toString()

or

1..toString()

since the tokenizer knows that the second dot must be a token on its own, and not part of the number literal.