MapComplete/UI/Base/Lazy.ts

import BaseUIElement from "../BaseUIElement"

export default class Lazy extends BaseUIElement {
    private readonly _f: () => BaseUIElement

    constructor(f: () => BaseUIElement) {
        super()
        this._f = f
    }

    protected InnerConstructElement(): HTMLElement {
        // The caching of the BaseUIElement will guarantee that _f will only be called once
        return this._f().ConstructElement()
    }
}