Typescript: names of types and variables do not allow a reserved word to be used.

Created on 10 Sep 2018 · 3Comments · Source: microsoft/TypeScript

TypeScript Version: 3.1.0-dev.20180907

Search Terms:
names of types still parse keywords
type name interprets reserved words
declaring names cannot use keywords
reserved words cannot be used

Code

export namespace Problematic {
    export type 'class' = string | null;
    export var 'class': string | null = "";
    export const 'class': string | null = "";
    export ['class']: string | null = "";
    type 'class' = string;
    export type class = string | null;
    export var class: string | null = "";
    export var class = "";
}
export interface StrangelyOk {
    class: Problematic.class;
}

Expected behavior:
a member would be declared with the name of 'class', and I could access that member from other objects
Actual behavior:
errors occur that prohibit the name being declared, however objects that attempt to access the member simply claim that it does not have a member of that name exported.
Playground Link:
Playground
Related Issues:
None found

Question

Source

puppy0cam

Most helpful comment

I'm converting some JS code to TS. The JS module I'm working on exports a function with a "null" attribute added. The obvious export const null = ... produces a syntax error, and I've ended up here trying to find a workaround.

The solution @DanielRosenwasser gave may have worked in an earlier version of TypeScript, but in latest (3.2.4) I get a syntax error with this example code:

export namespace MyNamespace {
    const _null = "My Constant";
    export {_null as null};
}

This is the error I receive:

error TS1194: Export declarations are not permitted in a namespace.
3     export {_null as null};

pineapplemachine on 30 Jan 2019

👍4

All 3 comments

You can use an export declaration with a local name that's not reserved, and any identifier for an exported name.

declare namespace Foo {
    var _class;
    export { _class as class };
}

Foo.class

DanielRosenwasser on 11 Sep 2018

The solution @DanielRosenwasser gave may have worked in an earlier version of TypeScript, but in latest (3.2.4) I get a syntax error with this example code:

export namespace MyNamespace {
    const _null = "My Constant";
    export {_null as null};
}

This is the error I receive:

error TS1194: Export declarations are not permitted in a namespace.
3     export {_null as null};

pineapplemachine on 30 Jan 2019

👍4

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