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- /**
- * @license
- * Copyright 2019 Google Inc.
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
- /**
- * Determine whether the current browser supports passive event listeners, and
- * if so, use them.
- */
- export function applyPassive(globalObj) {
- if (globalObj === void 0) { globalObj = window; }
- return supportsPassiveOption(globalObj) ?
- { passive: true } :
- false;
- }
- function supportsPassiveOption(globalObj) {
- if (globalObj === void 0) { globalObj = window; }
- // See
- // https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener
- var passiveSupported = false;
- try {
- var options = {
- // This function will be called when the browser
- // attempts to access the passive property.
- get passive() {
- passiveSupported = true;
- return false;
- }
- };
- var handler = function () { };
- globalObj.document.addEventListener('test', handler, options);
- globalObj.document.removeEventListener('test', handler, options);
- }
- catch (err) {
- passiveSupported = false;
- }
- return passiveSupported;
- }
- //# sourceMappingURL=events.js.map
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