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A simple base class for creating fast, lightweight web components

There is a newer version: 4.1.1

/**
 * @license
 * Copyright 2017 Google LLC
 * SPDX-License-Identifier: BSD-3-Clause
 */
var _a, _b;
/**
 * LitElement patch to support browsers without native web components.
 *
 * This module should be used in addition to loading the web components
 * polyfills via @webcomponents/webcomponentjs. When using those polyfills
 * support for polyfilled Shadow DOM is automatic via the ShadyDOM polyfill, but
 * support for Shadow DOM like css scoping is opt-in. This module uses ShadyCSS
 * to scope styles defined via the `static styles` property and styles included
 * in the render method. There are some limitations to be aware of:
 * * only styles that are included in the first render of a component are scoped.
 * * In addition, support for the deprecated `@apply` feature of ShadyCSS is
 * only provided for styles included in the template and not styles provided
 * via the static styles property.
 * * Lit parts cannot be used in styles included in the template.
 *
 * @packageDocumentation
 */
import '@lit/reactive-element/polyfill-support.js';
import 'lit-html/polyfill-support.js';
// Note, explicitly use `var` here so that this can be re-defined when
// bundled.
// eslint-disable-next-line no-var
var DEV_MODE = true;
var polyfillSupport = function (_a) {
    var LitElement = _a.LitElement;
    // polyfill-support is only needed if ShadyCSS or the ApplyShim is in use
    // We test at the point of patching, which makes it safe to load
    // webcomponentsjs and polyfill-support in either order
    if (window.ShadyCSS === undefined ||
        (window.ShadyCSS.nativeShadow && !window.ShadyCSS.ApplyShim)) {
        return;
    }
    // console.log(
    //   '%c Making LitElement compatible with ShadyDOM/CSS.',
    //   'color: lightgreen; font-style: italic'
    // );
    LitElement._$handlesPrepareStyles = true;
    /**
     * Patch to apply adoptedStyleSheets via ShadyCSS
     */
    var litElementProto = LitElement.prototype;
    var createRenderRoot = litElementProto.createRenderRoot;
    litElementProto.createRenderRoot = function () {
        // Pass the scope to render options so that it gets to lit-html for proper
        // scoping via ShadyCSS. This is needed under Shady and also Shadow DOM,
        // due to @apply.
        this.renderOptions.scope = this.localName;
        return createRenderRoot.call(this);
    };
};
if (DEV_MODE) {
    (_a = globalThis.litElementPolyfillSupportDevMode) !== null && _a !== void 0 ? _a : (globalThis.litElementPolyfillSupportDevMode = polyfillSupport);
}
else {
    (_b = globalThis.litElementPolyfillSupport) !== null && _b !== void 0 ? _b : (globalThis.litElementPolyfillSupport = polyfillSupport);
}
//# sourceMappingURL=polyfill-support.js.map