systrace/catapult/third_party/polymer/components/shadycss/src/common-utils.js

/**
@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
*/

'use strict';

import { MIXIN_MATCH, VAR_ASSIGN } from './common-regex.js';

/**
 * @param {Element} element
 * @param {Object=} properties
 */
export function updateNativeProperties(element, properties) {
  // remove previous properties
  for (let p in properties) {
    // NOTE: for bc with shim, don't apply null values.
    if (p === null) {
      element.style.removeProperty(p);
    } else {
      element.style.setProperty(p, properties[p]);
    }
  }
}

/**
 * @param {Element} element
 * @param {string} property
 * @return {string}
 */
export function getComputedStyleValue(element, property) {
  /**
   * @const {string}
   */
  const value = window.getComputedStyle(element).getPropertyValue(property);
  if (!value) {
    return '';
  } else {
    return value.trim();
  }
}

/**
 * return true if `cssText` contains a mixin definition or consumption
 * @param {string} cssText
 * @return {boolean}
 */
export function detectMixin(cssText) {
  const has = MIXIN_MATCH.test(cssText) || VAR_ASSIGN.test(cssText);
  // reset state of the regexes
  MIXIN_MATCH.lastIndex = 0;
  VAR_ASSIGN.lastIndex = 0;
  return has;
}