Question

I’ve been trying to wrap my head around javascript prototypal inheritance and while reading through John Resig’s book “Pro Javascript Techniques”, I was trying things like this:

alert("me".constructor); //Correctly return String
alert(alert.constructor); //Correctly return Function

However,

alert(55.constructor);//I was expecting Number, but it returns error "SyntaxError: identifier starts immediately after numeric literal" in FF and in IE, it says it is expecting ")"

I also tried other functions that should work on a number, like toFixed() toPrecision() and even toString() but nothing works!

Can someone please explain this behavior?

Answer 1

Put () around the number, like this:

alert((55).constructor);

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Taken from the comments:

The parser is expecting a decimal number, but fails because it sees the letter “c” instead. Alternatively, 55..constructor would also work (because 55. is just 55.0 or 55).