@polymer-vis/decorator-transformer

Replace PolymerElement or LitElement decorators (@customElement, @property) in your typescript codes.

Before

@customElement("x-foo")
class XFoo extends HTMLElement {
  static get properties() {
    return {};
  }

  /** some comment */
  @property
  public a: string;
}

After

class XFoo {
  static get properties() {
    return {
      /*Some comment*/
      prop1: String
    };
  }
}
customElements.define("x-foo", XFoo);

TODO:

• Fix error when declaration is true if properties is not declared.
• Fix output formatting.

Usage

npm i -D @polymer-vis/decorator-transformer

Important Note

If declaration for your tsconfig.json is set to true, you MUST include the properties getAccessor in your class:

class SomeElement {
  @property
  prop1: string;

  // this must be include if u are emitting
  // type declaration.
  static get properties() {
    return {};
  }
}

With ttypescript

Update your tsconfig.json with @polymer-vis/decorator-transformer plugin. Then run ttsc to compile your typescript sources.

{
  "compilerOptions": {
    "plugins": [
      { "transform": "@polymer-vis/decorator-transformer", "type": "config" }
    ]
  }
}

With typescript compiler API

import * as ts from "typescript";
import decoratorTransformer from "@polymer-vis/decorator-transformer";

let source = `
@customElement('x-foo')
class XFoo extends HTMLElement {
  static get properties() { return {}; }

  @property
  public a: string;

  @property
  public b: number;

  @property
  public c: boolean;

  @property
  public d: string[];

  @property
  public e: Array<Date>;

  @property
  public f: object;

  public g: string;
}
`;
let result = ts.transpileModule(source, {
  compilerOptions: { module: ts.ModuleKind.CommonJS },
  transformers: { before: [decoratorTransformer()] }
});

console.log(result.outputText);

Credits

The source codes are originally by 43081j at lit-element PR#145. I made some minor improvements to replace @property with the corresponding comment and property declarations (if present).