Unable to make class generic with JSDoc

[JoelEinbinder]

TypeScript Version: 2.6.0-dev.20170829

/**
 * @template T
 */
class MyArray {
  constructor() {
    /** @type {Array<T>} */
    this.array = [];
  }
}
/** @type {MyArray<string>} */
let x = new MyArray();

Expected behavior:
x should contain an array of strings.

Actual behavior:
[js] Cannot find name 'T'.
[js] Type 'MyArray' is not generic.

[kitsonk]

Could this be a duplicate of #17140?

[sandersn]

Just to make sure, this is in a .js file, right?

[JoelEinbinder]

Yes, this is in a .js file.

My compilerOptions:

{
    "noEmit": true,
    "allowJs": true,
    "checkJs": true,
    "target": "es2017"
}