LayoutWorlet.js

class simpleLayout {
  static get inputProperties() { return [ /* ... */ ]; }

  static get childrenInputProperties() { return [ /* ... */ ]; }
  
  static get layoutOptions() {
    return { /* ... */ };
  }

  *intrinsicSizes(children, edges, styleMap) {
    // ...
  }

  *layout(children, edges, constraints, styleMap, breakToken) {
    // ...
  }
}

registerLayout('sample-layout', simpleLayout);