detectors.ts

/*
 * Copyright (c) 2022 Snowplow Analytics Ltd, 2010 Anthon Pang
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Checks whether sessionStorage is available, in a way that
 * does not throw a SecurityError in Firefox if "always ask"
 * is enabled for cookies (https://github.com/snowplow/snowplow/issues/163).
 */
export function hasSessionStorage() {
  try {
    return !!window.sessionStorage;
  } catch (e) {
    return true; // SecurityError when referencing it means it exists
  }
}

/*
 * Checks whether localStorage is available, in a way that
 * does not throw a SecurityError in Firefox if "always ask"
 * is enabled for cookies (https://github.com/snowplow/snowplow/issues/163).
 */
export function hasLocalStorage() {
  try {
    return !!window.localStorage;
  } catch (e) {
    return true; // SecurityError when referencing it means it exists
  }
}

/*
 * Checks whether localStorage is accessible
 * sets and removes an item to handle private IOS5 browsing
 * (http://git.io/jFB2Xw)
 */
export function localStorageAccessible() {
  var mod = 'modernizr';
  if (!hasLocalStorage()) {
    return false;
  }
  try {
    const ls = window.localStorage;
    ls.setItem(mod, mod);
    ls.removeItem(mod);
    return true;
  } catch (e) {
    return false;
  }
}