How do you specify that a class property is an integer?

Question

I\'m experimenting with TypeScript, and in the process of creating a class with an ID field that should be an integer, I have gotten a

Answer 1

Well, as you have seen, typescript haven't float data type such as javascript language. Only have the number that cover all int and double at same time; maybe you must make a function that take a number and check it if it's a int or double, by returning some state in case error/success. Something like this as method of your class:

function SetN(x:number) {
   var is_int = parseInt(x) === parseFloat(x);
   if(is_int) this.n = x;
   return is_int;
}

//..
y = 10.5;
if(SetN(y)) {
  //OK
} else {
   //error not set y isn't a int
}

Note: it doest not works for 10.0 e.g. If you want no really it, maybe you must conver it to string and try to find a ..

Answer 2

int was reserved for future use keyword in earlier versions of javascript (ECMAScript if you prefer). But it is a valid word now (where "now" equates to "in the latest spec").

For instance, in 262 it was still reserved, http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf

It would make nice addition to typescript to have an int datatype implemented but with all compile-time type checking and casting rules available.