operator === cannot be applied to types false and true

[zerkms]

TypeScript Version: 3.0.0-dev.201xxxxx

Search Terms:

Code

var a = false;

if (a === true) {
    console.log('foo')
}

Expected behavior:
Given typescript is a superset of JS it must compile

Actual behavior:
It fails with the operator === cannot be applied to types false and true

Playground Link:
https://www.typescriptlang.org/play/#src=var%20a%20%3D%20false%3B%0D%0A%0D%0Aif%20(a%20%3D%3D%3D%20true)%20%7B%0D%0A%20%20%20%20console.log('foo')%0D%0A%7D

Related Issues:
It was at least reported at #11178 but for some reason the original poster has closed it

[Zzzen]

var a = 1;
a = "1"

is valid js code, and yet it should not compile.

[zerkms]

Then the main page with its

TypeScript is a typed superset of JavaScript that compiles to plain JavaScript.

and documentation should be corrected correspondingly?

[mhegazy]

Given typescript is a superset of JS it must compile

it does. the compiler will generate JavaScript fro your input that is identical. Compiler errors do not stop the generation of output. the compiler will however warn you about possible issues. that applies to almost all errors in TS.

[zerkms]

Compiler errors do not stop the generation of output

unless --noEmitOnError is used.

But I see the point, thanks.