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lit-element.ts
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lit-element.ts
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/**
* @license
* Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
* This code may only be used under the BSD style license found at
* http://polymer.github.io/LICENSE.txt
* The complete set of authors may be found at
* http://polymer.github.io/AUTHORS.txt
* The complete set of contributors may be found at
* http://polymer.github.io/CONTRIBUTORS.txt
* Code distributed by Google as part of the polymer project is also
* subject to an additional IP rights grant found at
* http://polymer.github.io/PATENTS.txt
*/
import {TemplateResult} from 'lit-html';
import {render} from 'lit-html/lib/shady-render';
import {PropertyValues, UpdatingElement} from './lib/updating-element.js';
export * from './lib/updating-element.js';
export * from './lib/decorators.js';
export {html, svg} from 'lit-html/lit-html';
export class LitElement extends UpdatingElement {
/**
* Render method used to render the lit-html TemplateResult to the element's
* DOM.
* @param {TemplateResult} Template to render.
* @param {Element|DocumentFragment} Node into which to render.
* @param {String} Element name.
*/
static render = render;
/**
* Updates the element. This method reflects property values to attributes
* and calls `render` to render DOM via lit-html. Setting properties inside
* this method will *not* trigger another update.
* * @param _changedProperties Map of changed properties with old values
*/
protected update(changedProperties: PropertyValues) {
super.update(changedProperties);
const templateResult = this.render() as any;
if (templateResult instanceof TemplateResult) {
(this.constructor as typeof LitElement)
.render(templateResult, this.renderRoot!,
{scopeName : this.localName!, eventContext : this});
}
}
/**
* Invoked on each update to perform rendering tasks. This method must return
* a lit-html TemplateResult. Setting properties inside this method will *not*
* trigger the element to update.
*/
protected render(): TemplateResult|void {}
}