1.toString() SyntaxError in Javascript

Question

Why the first line below gives error although the second and third lines work fine?

1.toString(); // SyntaxError
(1).toString(); // OK
1[\'toString\'](); //          


        

Answer 1

The parser is trying to treat 1. as the start of a floating-point literal -- only toString turns it into an invalid number.

Compare with:

1.0.toString()