All files / core/util VisibilityMonitor.ts

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
12x
12x
 
 
 
 
 
 
12x
 
 
12x
31x
 
 
 
31x
 
 
31x
 
 
 
31x
 
31x
31x
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
31x
 
31x
31x
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
12x
31x
31x
 
12x
 
/**
 * Copyright 2017 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
import { EventEmitter } from './EventEmitter';
import { assert } from '@firebase/util';
 
declare const document: any;
 
/**
 * @extends {EventEmitter}
 */
export class VisibilityMonitor extends EventEmitter {
  private visible_: boolean;
 
  static getInstance() {
    return new VisibilityMonitor();
  }
 
  constructor() {
    super(['visible']);
    let hidden: string;
    let visibilityChange: string;
    Eif (
      typeof document !== 'undefined' &&
      typeof document.addEventListener !== 'undefined'
    ) {
      Eif (typeof document['hidden'] !== 'undefined') {
        // Opera 12.10 and Firefox 18 and later support
        visibilityChange = 'visibilitychange';
        hidden = 'hidden';
      } else if (typeof document['mozHidden'] !== 'undefined') {
        visibilityChange = 'mozvisibilitychange';
        hidden = 'mozHidden';
      } else if (typeof document['msHidden'] !== 'undefined') {
        visibilityChange = 'msvisibilitychange';
        hidden = 'msHidden';
      } else if (typeof document['webkitHidden'] !== 'undefined') {
        visibilityChange = 'webkitvisibilitychange';
        hidden = 'webkitHidden';
      }
    }
 
    // Initially, we always assume we are visible. This ensures that in browsers
    // without page visibility support or in cases where we are never visible
    // (e.g. chrome extension), we act as if we are visible, i.e. don't delay
    // reconnects
    this.visible_ = true;
 
    Eif (visibilityChange) {
      document.addEventListener(
        visibilityChange,
        () => {
          const visible = !document[hidden];
          if (visible !== this.visible_) {
            this.visible_ = visible;
            this.trigger('visible', visible);
          }
        },
        false
      );
    }
  }
 
  /**
   * @param {!string} eventType
   * @return {Array.<boolean>}
   */
  getInitialEvent(eventType: string): boolean[] {
    assert(eventType === 'visible', 'Unknown event type: ' + eventType);
    return [this.visible_];
  }
}