Date constructor should accept 'null' as a valid value when using strictNullChecks

[guncha]

TypeScript Version: nightly 2.1.0-dev.20161103

Code

let t = new Date(null) // Argument of type 'null' is not assignable to parameter of type 'string'

According to the spec, the result is going to be the same as new Date(+0).

http://www.ecma-international.org/ecma-262/5.1/#sec-15.9.3.2

[RyanCavanaugh]

This doesn't seem at all desirable. It would imply it's legal to call new Date providing a string | null, when you almost certainly would want to have null-checked that value.

[guncha]

Upon further thought, I tend to agree. It's not matching the spec, but developer experience trumps that. I can always do this to make it explicit:

let x: string | null
let t = new Date(x || 0)

[RyanCavanaugh]

Note that the ES spec defines all sorts of behavior that we don't want to allow to pass typechecking; e.g. the behavior of { } / "hello world" is well-defined according to the spec.