@material/dom/events.js

DOM manipulation utilities for Material Components for the web

/**
 * @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;
}
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