Support parsing import.meta

[justinfagnani]

import.meta does not parse. import.meta is stage 3 and implemented in Chrome/V8. See the TC39 proposal here: https://github.com/tc39/proposal-import-meta

TypeScript Version: 2.7.0-dev.201xxxxx

Search Terms:
import.meta

Code

const u = import.meta.url;

Expected behavior:

import.meta at least parses when output is esnext.

For downlevel emit, specific meta-properties like import.meta.url, would presumably have to be handled differently. For import.meta.url a project could be given a base URL from which module base URLs are calculated from given their path.

Or a custom transform could be used. Any solution requires that import.meta parse though.

Actual behavior:

Syntax error.

Playground Link:

http://www.typescriptlang.org/play/#src=const%20i%20%3D%20import.meta.url%3B

Related Issues:

[DanielRosenwasser]

What would the type be? any? Changing it after the fact would be breaking.

[justinfagnani]

As far as I know, import.meta is host defined, so by default I don't think it could be anything other than object. The node and dom typings should define import.meta.url as string.

[mhegazy]

As far as I know, import.meta is host defined, so by default I don't think it could be anything other than object. The node and dom typings should define import.meta.url as string.

I would say the type should be:

interface ImportMeta {
    [x: string]: any;
}

This allows say node to define some well-known import.meta fields.

[justinfagnani]

I guess there are two options:

interface ImportMeta {
    [x: string]: any;
}

and

interface ImportMeta {
}

The latter would require that you import some typings that define specific fields, or cast your way out of an error.