Property X never defined on Y

I’m running into this issue,

// index.js
import Type from './Type'

const t = new Type()
t.fromXML('Hello world', { name: 'test', optional: false })
console.log(t.type)

// Type.js
/**
 * A representation of a type.
 * @extends {typal.Type}
 */
export default class Type {
  fromXML(content, props) {
    this.type = props.name
    this.desc = content
  }
}

// depack/prop/externs.js
/** @const */
var typal = {}
/**
 * @typedef {{ type: string, desc: string }}
 */
typal.Type

I’m pretty sure if something extends an extern, it should preserve its own methods as well.

-jar compiler.jar --compilation_level ADVANCED \
--language_out ECMASCRIPT_2017 \
--formatting PRETTY_PRINT --externs depack/prop/externs.js \
--module_resolution NODE \
--js depack/prop/index.js depack/prop/Type.js 

Compiles fine though

class a {
}
;const b = new a;
b.type = "test";
b.desc = "Hello world";
console.log(b.type);

Don’t want the warning though.

depack/prop/index.js:4: WARNING - Property fromXML never defined on Type
t.fromXML('Hello world', { name: 'test', optional: false })
  ^^^^^^^

0 error(s), 1 warning(s), 87.0% typed

[brad4d]

@zavr-1 I’m glad you’ve found a solution.

[zavr-1]

hi yeah i’ve figured it out I could do that thank you, did something like that (without externs, because the whole point of externs was to avoid an error saying that I cannot assign to uninitialised properties on a structure, so I just initialise them all in the constructor to null. , please feel free to close this.

/**
 * A representation of a type.
 */
export default class Type {
  constructor() {
   /**
     * The name of the type.
     * @type {?string}
     */
    this.name = null
    /** @type {?string} */
    this.type = null
  }
}