-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathindex.html
More file actions
1049 lines (742 loc) · 48.8 KB
/
index.html
File metadata and controls
1049 lines (742 loc) · 48.8 KB
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
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
<!DOCTYPE html>
<html lang="zh">
<head>
<meta charset="utf-8">
<title>GeminiKnight的博客</title>
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1" />
<meta property="og:type" content="website">
<meta property="og:title" content="GeminiKnight的博客">
<meta property="og:url" content="https://geminiknight.github.io/index.html">
<meta property="og:site_name" content="GeminiKnight的博客">
<meta property="og:locale" content="zh-CN">
<meta name="twitter:card" content="summary">
<meta name="twitter:title" content="GeminiKnight的博客">
<link rel="icon" href="/images/favicon.svg">
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bulma@0.7.2/css/bulma.css">
<link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.4.1/css/all.css">
<link rel="stylesheet" href="https://fonts.googleapis.com/icon?family=Material+Icons">
<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Ubuntu:400,600|Source+Code+Pro">
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/highlight.js@9.12.0/styles/atom-one-light.css">
<link rel="stylesheet" href="/css/style.css">
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/lightgallery@1.6.8/dist/css/lightgallery.min.css">
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/justifiedGallery@3.7.0/dist/css/justifiedGallery.min.css">
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/outdatedbrowser@1.1.5/outdatedbrowser/outdatedbrowser.min.css">
<style>body{opacity: 0}</style>
</head>
<body class="is-3-column">
<nav class="navbar navbar-main">
<div class="container">
<div class="navbar-brand is-flex-center">
<a class="navbar-item navbar-logo" href="/">
<img src="/images/logo.svg" alt="" height="28">
</a>
</div>
<div class="navbar-menu">
<div class="navbar-start">
<a class="navbar-item is-active"
href="/">Home</a>
<a class="navbar-item"
href="/archives">Archives</a>
<a class="navbar-item"
href="/categories">Categories</a>
<a class="navbar-item"
href="/tags">Tags</a>
<a class="navbar-item"
href="/about">About</a>
</div>
<div class="navbar-end">
<a class="navbar-item search" title="搜索" href="javascript:;">
<i class="material-icons is-size-5">search</i>
</a>
</div>
</div>
</div>
</nav>
<section class="section">
<div class="container">
<div class="columns main">
<div class="column is-8-tablet is-8-desktop is-6-widescreen has-order-2">
<div class="card">
<div class="card-content article ">
<div class="level article-meta is-size-7 is-uppercase is-mobile is-overflow-x-auto">
<div class="level-left">
<time class="level-item has-text-grey" datetime="2018-11-21T11:33:58.000Z">2018-11-21</time>
<span class="level-item has-text-grey">
几秒 读完 (大约 41 个字)
</span>
</div>
</div>
<h1 class="title is-size-3 is-size-4-mobile has-text-weight-normal">
<a class="has-link-black-ter" href="/2018/11/21/self-introduce/">我的自我介绍</a>
</h1>
<div class="content">
<p>欢迎来到GeminiKnight的个人博客，这是我的第一篇博文，我会简单介绍一下自己</p>
<h2 id="基本信息"><a href="#基本信息" class="headerlink" title="基本信息"></a>基本信息</h2><figure class="highlight bash hljs"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">$ hexo new <span class="hljs-string">"My New Post"</span></span><br></pre></td></tr></table></figure>
</div>
</div>
</div>
<div class="card">
<div class="card-content article ">
<div class="level article-meta is-size-7 is-uppercase is-mobile is-overflow-x-auto">
<div class="level-left">
<time class="level-item has-text-grey" datetime="2018-11-14T14:40:28.000Z">2018-11-14</time>
<span class="level-item has-text-grey">
5 分钟 读完 (大约 701 个字)
</span>
</div>
</div>
<h1 class="title is-size-3 is-size-4-mobile has-text-weight-normal">
<a class="has-link-black-ter" href="/2018/11/14/hello-world/">JS数据类型，浅拷贝和深拷贝</a>
</h1>
<div class="content">
<p>JavaScript共有7种数据类型，分为两种：基本类型和引用类型。基本类型包括Null，Undefined，Boolean，Number，String和ES6中新增的<a href="http://es6.ruanyifeng.com/#docs/symbol" target="_blank" rel="noopener">symbol</a>;引用类型统称为Object(包括Array，Date，RegExp，Function)。基本类型值和引用类型值有很多不同之处：<br>1.基本类型值在内存中占据固定大小的空间，因此会被保存在栈内存中;引用类型的值是对象，保存在堆内存中(堆和栈都是内存中划分出来用来存储的区域,<br>栈（stack）为自动分配的内存空间，它由系统自动释放；而堆（heap）则是动态分配的内存，大小不定也不会自动释放);而且包含引用类型值的变量实际上包含的并不是对象本身，而是指向该对象的指针。<br>2.从一个变量向另一个变量复制基本类型值，会创建这个值的一个副本，二者不会互相影响。而从一个变量向另一个变量复制引用类型的值，复制的其实是指针，因此两个变量实际上指向同一个对象。<br>3.基本类型的值进行比较时比较的是值是否相等，而引用类型值在比较时比较的是存储地址是否相等</p>
<p>确定一个值是哪一种基本类型值可以用typeof 操作符：<br><figure class="highlight plain hljs"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br></pre></td><td class="code"><pre><span class="line">var s = 'jack';</span><br><span class="line">var b = false;</span><br><span class="line">var i = 23;</span><br><span class="line">var u;</span><br><span class="line">var n = null;</span><br><span class="line">var o = new Object();</span><br><span class="line"></span><br><span class="line">console.log(typeof s); // string</span><br><span class="line">console.log(typeof b); // bolean</span><br><span class="line">console.log(typeof i); // number</span><br><span class="line">console.log(typeof u); // undefined</span><br><span class="line">console.log(typeof n); // obejct</span><br><span class="line">console.log(typeof o); // object</span><br></pre></td></tr></table></figure></p>
<p>对于引用类型值的时候，typeof均返回object。可以使用instanceof（是···的实例）操作符：<br><figure class="highlight plain hljs"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line">person instanceof Array; //person是Array的是实例么？</span><br><span class="line">person instanceof RegExp; //person是RegExp的是实例么？</span><br><span class="line">person instanceof Object; //person是Object的是实例么？</span><br></pre></td></tr></table></figure></p>
<p>基本数据类型的赋值是传值,在内存中新开辟一段栈内存，然后再把再将值赋值到新的栈中：<br><figure class="highlight plain hljs"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line">var a = 10;</span><br><span class="line">var b = a;</span><br><span class="line">a ++ ;</span><br><span class="line">console.log(a); // 11</span><br><span class="line">console.log(b); // 10</span><br></pre></td></tr></table></figure></p>
<p>而引用类型的赋值是传（地）址,只是改变指针的指向，例如，也就是说引用类型的赋值是对象保存在栈中的地址的赋值，这样的话两个变量就指向同一个对象，因此两者之间操作互相有影响<br><figure class="highlight plain hljs"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line">var a = {}; // a保存了一个空对象的实例</span><br><span class="line">var b = a; // a和b都指向了这个空对象</span><br><span class="line">a.name = 'jozo';</span><br><span class="line">console.log(a.name); // 'jozo'</span><br><span class="line">console.log(b.name); // 'jozo'</span><br><span class="line">b.age = 22;</span><br><span class="line">console.log(b.age);// 22</span><br><span class="line">console.log(a.age);// 22</span><br><span class="line">console.log(a == b);// true</span><br></pre></td></tr></table></figure></p>
</div>
</div>
</div>
<div class="card">
<div class="card-content article ">
<div class="level article-meta is-size-7 is-uppercase is-mobile is-overflow-x-auto">
<div class="level-left">
<time class="level-item has-text-grey" datetime="2018-11-14T14:14:22.000Z">2018-11-14</time>
<span class="level-item has-text-grey">
1 分钟 读完 (大约 178 个字)
</span>
</div>
</div>
<h1 class="title is-size-3 is-size-4-mobile has-text-weight-normal">
<a class="has-link-black-ter" href="/2018/11/14/interview/"></a>
</h1>
<div class="content">
<p>JS垃圾回收机制：JS具有自动垃圾回收机制，也就是说执行环境会负责管理代码执行过程中使用的内存。垃圾回收的原理很简单：找出那些不在继续使用的的变量，释放其所占用的内存。主要的回收机制有两种：标记清除和引用计数。</p>
<p>1.标记清除</p>
<p>2.引用计数：<br>跟踪记录每个值被引用的次数：当声明一个变量并将一个引用类型值赋给该变量时，这个值得引用次数加一。（存在循环引用问题，导致内存泄漏。）</p>
</div>
</div>
</div>
<div class="card">
<div class="card-content article ">
<div class="level article-meta is-size-7 is-uppercase is-mobile is-overflow-x-auto">
<div class="level-left">
<time class="level-item has-text-grey" datetime="2018-11-06T08:04:04.000Z">2018-11-06</time>
<span class="level-item has-text-grey">
10 分钟 读完 (大约 1498 个字)
</span>
</div>
</div>
<h1 class="title is-size-3 is-size-4-mobile has-text-weight-normal">
<a class="has-link-black-ter" href="/2018/11/06/storage/">cookie,sessionStorage,localStorage</a>
</h1>
<div class="content">
<h2 id="1-cookie"><a href="#1-cookie" class="headerlink" title="1. cookie"></a>1. cookie</h2><h4 id="1-1-简介"><a href="#1-1-简介" class="headerlink" title="1.1 简介"></a>1.1 简介</h4><p><a href="https://developer.mozilla.org/zh-CN/docs/Web/HTTP/Cookies" target="_blank" rel="noopener">cookie</a>即HTTP cookie，是服务器发送到用户浏览器并保存在本地的一小块数据，它会在浏览器下次向同一服务器再发起请求时被携带并发送到服务器上。通常，它用于告知服务端两个请求是否来自同一浏览器，如保持用户的登录状态。Cookie使基于无状态的HTTP协议记录稳定的状态信息成为了可能。<br>Cookie主要用于以下三个方面：</p>
<ul>
<li>会话状态管理（如用户登录状态、购物车、游戏分数或其它需要记录的信息）</li>
<li>个性化设置（如用户自定义设置、主题等）</li>
<li>浏览器行为跟踪（如跟踪分析用户行为等）</li>
</ul>
<p>当服务器收到HTTP请求时，服务器可以在响应头里面添加一个Set-Cookie选项。浏览器收到响应后通常会保存下Cookie，之后对该服务器每一次请求中都通过Cookie请求头部将Cookie信息发送给服务器。另外，Cookie的过期时间、域、路径、有效期、适用站点都可以根据需要来指定。</p>
<p>服务器通过在响应头部使用Set-Cookie向用户代理（一般是浏览器）发送Cookie信息<br><figure class="highlight plain hljs"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">Set-Cookie: <cookie名>=<cookie值></span><br></pre></td></tr></table></figure></p>
<p>如一个响应头部可能如下:<br><figure class="highlight plain hljs"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line">HTTP/1.0 200 OK</span><br><span class="line">Content-type: text/html</span><br><span class="line">Set-Cookie: yummy_cookie=choco</span><br><span class="line">Set-Cookie: tasty_cookie=strawberry</span><br><span class="line"></span><br><span class="line">[页面内容]</span><br></pre></td></tr></table></figure></p>
<p>之后，浏览器对该服务器发起的每一次新请求都会将之前保存的Cookie信息通过Cookie请求头部再发送给服务器，如<br><figure class="highlight plain hljs"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line">GET /sample_page.html HTTP/1.1</span><br><span class="line">Host: www.example.org</span><br><span class="line">Cookie: yummy_cookie=choco; tasty_cookie=strawberry</span><br></pre></td></tr></table></figure></p>
<h4 id="1-2-cookie的限制"><a href="#1-2-cookie的限制" class="headerlink" title="1.2 cookie的限制"></a>1.2 cookie的限制</h4><p>cookie 在性质上是绑定在特定的域名下的。当设定了一个 cookie 后，再给创建它的域名发送请求时， 6 都会包含这个 cookie。这个限制确保了储存在 cookie 中的信息只能让批准的接受者访问，而无法被其他域访问<br>由于 cookie 是存在客户端计算机上的，还加入了一些限制确保 cookie 不会被恶意使用，同时不会占 据太多磁盘空间。每个域的 cookie 总数是有限的，不过浏览器之间各有不同：</p>
<ul>
<li>Firefox 和IE7 和之后版本限制每个域最多 50 个 cookie</li>
<li>Opera 限制每个域最多 30 个 cookie</li>
<li>Safari 和 Chrome 对于每个域的 cookie 数量限制没有硬性规定<br>当超过单个域名限制之后还要再设置 cookie，浏览器就会清除以前设置的 cookie。浏览器中对于 cookie 的尺寸也有限制。大多数浏览器都有大约 4096B(加减 1)的长度限制。为了 最佳的浏览器兼容性，最好将整个 cookie 长度限制在 4095B(含 4095)以内。如果你尝试创建超过最大尺寸限制的 cookie，那么该 cookie 会被悄无声息地丢掉</li>
</ul>
<h4 id="1-3-cookie的构成"><a href="#1-3-cookie的构成" class="headerlink" title="1.3 cookie的构成"></a>1.3 cookie的构成</h4><ul>
<li>名称：一个唯一确定 cookie 的名称</li>
<li>值：储存在 cookie 中的字符串值</li>
<li>域（Domain）：cookie 对于哪个域是有效的，即Cookie应该发送给哪些URL。所有向该域发送的请求中都会包含这个 cookie 信息。这个值可以包含子域(subdomain，如 <a href="http://www.wrox.com)，也可以不包含它" target="_blank" rel="noopener">www.wrox.com)，也可以不包含它</a>(如.wrox.com，则对于 wrox.com的所有子域都有效)。如果没有明确设定，那么这个域会被认作来自设置 cookie 的那个域（不包含子域名）。</li>
<li>路径（Path）：Path 标识指定了主机下的哪些路径可以接受Cookie（该URL路径必须存在于请求URL中）。以字符 %x2F (“/“) 作为路径分隔符，子路径也会被匹配。例如，设置 Path=/docs，则以下地址都会匹配：<ul>
<li>/docs</li>
<li>/docs/Web/</li>
<li>/docs/Web/HTTP</li>
</ul>
</li>
<li>失效时间：指定过期时间（Expires）或者有效期（Max-Age）确定cookie的有效期，其将在此时间过后被删除(只与用户代理的时间有关，与服务器时间无关)</li>
<li>安全标志：标记为 Secure 的Cookie只应通过被HTTPS协议加密过的请求发送给服务端<br>为避免跨域脚本 (XSS) 攻击，通过JavaScript的 Document.cookie API无法访问带有 HttpOnly 标记的Cookie，它们只应该发送给服务端</li>
</ul>
<p>例如：<br><figure class="highlight plain hljs"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line">HTTP/1.1 200 OK</span><br><span class="line">Content-type: text/html</span><br><span class="line">Set-Cookie: name=value; expires=Mon, 22-Nov-18 07:10:24 GMT; domain=.wrox.com ;secure;HttpOnly</span><br><span class="line">Other-header: other-header-value</span><br></pre></td></tr></table></figure></p>
<p>该头信息指定了一个叫做 name 的 cookie，它会在标准时间 2018 年 11 月 22 日 7:10:24 失效，同 时对于 <a href="http://www.wrox.com" target="_blank" rel="noopener">www.wrox.com</a> 和 wrox.com 的任何子域(如 p2p.wrox.com)都有效，并且只能通过HTTPS协议发送给服务器端，其只不能通过document.cookie访问</p>
<h2 id="2-sessionStorage和localStorage"><a href="#2-sessionStorage和localStorage" class="headerlink" title="2.sessionStorage和localStorage"></a>2.sessionStorage和localStorage</h2><p>二者的概念和用法都相似，不同之处在于 localStorage 里面存储的数据没有过期时间设置，而存储在 sessionStorage 里面的数据在页面会话结束时会被清除。页面会话在浏览器打开期间一直保持，并且重新加载或恢复页面仍会保持原来的页面会话。用法如下：<br><figure class="highlight plain hljs"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line">// 保存数据到sessionStorage</span><br><span class="line">sessionStorage.setItem('key', 'value');</span><br><span class="line"></span><br><span class="line">// 从sessionStorage获取数据,注意其得到的值为字符串类型</span><br><span class="line">var data = sessionStorage.getItem('key');</span><br><span class="line"></span><br><span class="line">// 从sessionStorage删除保存的数据</span><br><span class="line">sessionStorage.removeItem('key');</span><br><span class="line"></span><br><span class="line">// 从sessionStorage删除所有保存的数据</span><br><span class="line">sessionStorage.clear();</span><br></pre></td></tr></table></figure></p>
<figure class="highlight plain hljs"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line">// 保存数据到localStorage</span><br><span class="line">localStorage.setItem('key', 'value');</span><br><span class="line"></span><br><span class="line">// 从localStorage获取数据,注意其得到的值为字符串类型</span><br><span class="line">var data = localStorage.getItem('key');</span><br><span class="line"></span><br><span class="line">// 从localStorage删除保存的数据</span><br><span class="line">localStorage.removeItem('key');</span><br><span class="line"></span><br><span class="line">// 从localStorage删除所有保存的数据</span><br><span class="line">localStorage.clear();</span><br></pre></td></tr></table></figure>
</div>
</div>
</div>
<div class="card">
<div class="card-content article ">
<div class="level article-meta is-size-7 is-uppercase is-mobile is-overflow-x-auto">
<div class="level-left">
<time class="level-item has-text-grey" datetime="2018-07-12T16:00:00.000Z">2018-07-13</time>
<span class="level-item has-text-grey">
4 分钟 读完 (大约 667 个字)
</span>
</div>
</div>
<h1 class="title is-size-3 is-size-4-mobile has-text-weight-normal">
<a class="has-link-black-ter" href="/2018/07/13/third/">跨域问题详解</a>
</h1>
<div class="content">
<h2 id="1-1-跨域的概念"><a href="#1-1-跨域的概念" class="headerlink" title="1.1 跨域的概念"></a>1.1 跨域的概念</h2><p>出于安全原因，浏览器限制从脚本内发起的跨源HTTP请求。 例如，XMLHttpRequest和Fetch API遵循同源策略， 这意味着使用这些API的Web应用程序只能从加载应用程序的同一个域（协议，域名，端口号均相同）请求HTTP资源。<br>跨域的解决方案：</p>
<h3 id="1-图像Ping"><a href="#1-图像Ping" class="headerlink" title="1 图像Ping"></a>1 图像Ping</h3><p>我们知道，一个网业可以从任何网页中加载图像，不用担心跨域问题。所以可以利用<img>标签，动态创建图像，使用他们的onload和onerror事件处理程序来确定是否接收到了响应。<br>图像ping是与服务器进行简单.单向通讯的一种方式，请求的数据是通过查询字符串形式发送的，而响应可以使任何内容，但通常是像素图或204（No Content）响应（表示目前请求成功，没有内容）。通过图像Ping，浏览器无法得到任何数据，但通过侦听load和error事件，他们能知道响应是何时接受到的。<br><figure class="highlight plain hljs"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line">var img = new Image();</span><br><span class="line">img.onload = img.onerror = function(){</span><br><span class="line"> alert('done')</span><br><span class="line">}</span><br><span class="line">img.src = 'http://www.example.com/test?name=GeminiKnight'</span><br></pre></td></tr></table></figure></p>
<p>图像Ping常用于跟踪用户点击页面或动态广告曝光次数<br>主要有两个缺点： 1.只能发送GET请求（所以能发送的数据有限，也不安全）<br> 2.无法访问服务器的响应文本</p>
<h3 id="2-JSONP"><a href="#2-JSONP" class="headerlink" title="2 JSONP"></a>2 JSONP</h3><p>既然可以利用img标签实现跨域，那同样不受跨域限制的script标签是否也能实现跨域呢？答案是当然可以。JSONP（JSON with padding）由两部分内容组成：回调函数和数据。回调函数是当响应到来时应该在页面中调用的函数。回调函数的名字一般是在请求中指定的，而数据就是传入回调函数中的JSON数据，例如：<br><a href="http://freegeoip.net/json/?callback=handleResponse" target="_blank" rel="noopener">http://freegeoip.net/json/?callback=handleResponse</a><br>这里指定回调函数为handleResponse</p>
<p>function handleResponse(response){<br> alert(‘你的IP地址是’+ response.ip +’位于’ +’response.city’)<br>}<br>var script = document.createElement(‘script)<br>script.src = ‘<a href="http://freegeoip.net/json/?callback=handleResponse'" target="_blank" rel="noopener">http://freegeoip.net/json/?callback=handleResponse'</a><br>document.body.insertBefore(script,document.body.firstChild)<br><code>`</code><br>与图像Ping相比，他的优点在于可以直接访问响应文本，支持浏览器和服务器双向通信。不过它也有两点不足：1.JSONP是从其他域中加载代码，如果其他域不安全，可能会在代码中加载恶意代码<br> 2.很难判断JSONP请求成功与否。</p>
<h3 id="2-JSONP-1"><a href="#2-JSONP-1" class="headerlink" title="2 JSONP"></a>2 JSONP</h3>
</div>
</div>
</div>
</div>
<div class="column has-order-1 is-4-tablet is-4-desktop is-3-widescreen ">
<div class="card widget">
<div class="card-content">
<nav class="level">
<div class="level-item has-text-centered">
<div>
<img class="image is-128x128 has-mb-6" src="/images/avatar.png">
<p class="is-size-4 is-block">
薛建涛
</p>
<p class="is-size-6 is-block">
前端工程师
</p>
<p class="is-size-6 is-flex is-flex-center has-text-grey">
<i class="material-icons is-size-5 has-mr-7">location_on</i>
<span>上海</span>
</p>
</div>
</div>
</nav>
<nav class="level is-mobile">
<div class="level-item has-text-centered">
<div>
<p class="heading">
文章
</p>
<p class="title has-text-weight-normal">
5
</p>
</div>
</div>
<div class="level-item has-text-centered">
<div>
<p class="heading">
分类
</p>
<p class="title has-text-weight-normal">
0
</p>
</div>
</div>
<div class="level-item has-text-centered">
<div>
<p class="heading">
标签
</p>
<p class="title has-text-weight-normal">
0
</p>
</div>
</div>
</nav>
<div class="level">
<a class="level-item button is-link is-rounded" href="http://github.com/ppoffice">
关注我</a>
</div>
<div class="level is-mobile">
<a class="level-item button is-white" target="_blank"
title="Github" href="http://github.com/ppoffice">
<i class="fab fa-github"></i>
</a>
<a class="level-item button is-white" target="_blank"
title="Facebook" href="http://facebook.com">
<i class="fab fa-facebook"></i>
</a>
<a class="level-item button is-white" target="_blank"
title="Twitter" href="http://twitter.com">
<i class="fab fa-twitter"></i>
</a>
<a class="level-item button is-white" target="_blank"
title="Dribbble" href="http://dribbble.com">
<i class="fab fa-dribbble"></i>
</a>
<a class="level-item button is-white" target="_blank"
title="RSS" href="/">
<i class="fas fa-rss"></i>
</a>
</div>
</div>
</div>
<div class="card widget">
<div class="card-content">
<div class="menu">
<h3 class="menu-label">
分类
</h3>
<ul class="menu-list">
</ul>
</div>
</div>
</div>
<div class="card card-transparent is-hidden-widescreen">
<div class="card widget">
<div class="card-content">
<h3 class="menu-label">
最新文章
</h3>
<article class="media">
<a href="/2018/11/21/self-introduce/" class="media-left">
<p class="image is-64x64">
<img class="thumbnail" src="/images/thumbnail.svg" alt="我的自我介绍">
</p>
</a>
<div class="media-content">
<div class="content">
<div><time class="has-text-grey is-size-7 is-uppercase" datetime="2018-11-21T11:33:58.000Z">2018-11-21</time></div>
<a href="/2018/11/21/self-introduce/" class="has-link-black-ter is-size-6">我的自我介绍</a>
<p class="is-size-7 is-uppercase">
</p>
</div>
</div>
</article>
<article class="media">
<a href="/2018/11/14/hello-world/" class="media-left">
<p class="image is-64x64">
<img class="thumbnail" src="/images/thumbnail.svg" alt="JS数据类型，浅拷贝和深拷贝">
</p>
</a>
<div class="media-content">
<div class="content">
<div><time class="has-text-grey is-size-7 is-uppercase" datetime="2018-11-14T14:40:28.000Z">2018-11-14</time></div>
<a href="/2018/11/14/hello-world/" class="has-link-black-ter is-size-6">JS数据类型，浅拷贝和深拷贝</a>
<p class="is-size-7 is-uppercase">
</p>
</div>
</div>
</article>
<article class="media">
<a href="/2018/11/14/interview/" class="media-left">
<p class="image is-64x64">
<img class="thumbnail" src="/images/thumbnail.svg" alt="">
</p>
</a>
<div class="media-content">
<div class="content">
<div><time class="has-text-grey is-size-7 is-uppercase" datetime="2018-11-14T14:14:22.000Z">2018-11-14</time></div>
<a href="/2018/11/14/interview/" class="has-link-black-ter is-size-6"></a>
<p class="is-size-7 is-uppercase">
</p>
</div>
</div>
</article>
<article class="media">
<a href="/2018/11/06/storage/" class="media-left">
<p class="image is-64x64">
<img class="thumbnail" src="/images/thumbnail.svg" alt="cookie,sessionStorage,localStorage">
</p>
</a>
<div class="media-content">
<div class="content">
<div><time class="has-text-grey is-size-7 is-uppercase" datetime="2018-11-06T08:04:04.000Z">2018-11-06</time></div>
<a href="/2018/11/06/storage/" class="has-link-black-ter is-size-6">cookie,sessionStorage,localStorage</a>
<p class="is-size-7 is-uppercase">
</p>
</div>
</div>
</article>
<article class="media">
<a href="/2018/07/13/third/" class="media-left">
<p class="image is-64x64">
<img class="thumbnail" src="/images/thumbnail.svg" alt="跨域问题详解">
</p>
</a>
<div class="media-content">
<div class="content">
<div><time class="has-text-grey is-size-7 is-uppercase" datetime="2018-07-12T16:00:00.000Z">2018-07-13</time></div>
<a href="/2018/07/13/third/" class="has-link-black-ter is-size-6">跨域问题详解</a>
<p class="is-size-7 is-uppercase">
</p>
</div>
</div>
</article>
</div>
</div>
<div class="card widget">
<div class="card-content">
<div class="menu">
<h3 class="menu-label">
文档
</h3>
<ul class="menu-list">
<li>
<a class="level is-marginless" href="/archives/2018/11/">
<span class="level-start">
<span class="level-item">十一月 2018</span>
</span>
<span class="level-end">
<span class="level-item tag">4</span>
</span>
</a>
</li>
<li>
<a class="level is-marginless" href="/archives/2018/07/">
<span class="level-start">
<span class="level-item">七月 2018</span>
</span>
<span class="level-end">
<span class="level-item tag">1</span>
</span>
</a>
</li>
</ul>
</div>
</div>
</div>
<div class="card widget">
<div class="card-content">
<div class="menu">
<h3 class="menu-label">
标签
</h3>
<ul class="menu-list">
</ul>
</div>
</div>
</div>
</div>
</div>
<div class="column has-order-3 is-4-tablet is-4-desktop is-3-widescreen is-hidden-touch is-hidden-desktop-only">
<div class="card widget">
<div class="card-content">
<h3 class="menu-label">
最新文章
</h3>
<article class="media">
<a href="/2018/11/21/self-introduce/" class="media-left">
<p class="image is-64x64">
<img class="thumbnail" src="/images/thumbnail.svg" alt="我的自我介绍">
</p>
</a>
<div class="media-content">
<div class="content">
<div><time class="has-text-grey is-size-7 is-uppercase" datetime="2018-11-21T11:33:58.000Z">2018-11-21</time></div>
<a href="/2018/11/21/self-introduce/" class="has-link-black-ter is-size-6">我的自我介绍</a>
<p class="is-size-7 is-uppercase">
</p>
</div>
</div>
</article>
<article class="media">
<a href="/2018/11/14/hello-world/" class="media-left">
<p class="image is-64x64">
<img class="thumbnail" src="/images/thumbnail.svg" alt="JS数据类型，浅拷贝和深拷贝">
</p>
</a>
<div class="media-content">
<div class="content">
<div><time class="has-text-grey is-size-7 is-uppercase" datetime="2018-11-14T14:40:28.000Z">2018-11-14</time></div>
<a href="/2018/11/14/hello-world/" class="has-link-black-ter is-size-6">JS数据类型，浅拷贝和深拷贝</a>
<p class="is-size-7 is-uppercase">
</p>
</div>
</div>
</article>
<article class="media">
<a href="/2018/11/14/interview/" class="media-left">
<p class="image is-64x64">
<img class="thumbnail" src="/images/thumbnail.svg" alt="">
</p>
</a>
<div class="media-content">
<div class="content">
<div><time class="has-text-grey is-size-7 is-uppercase" datetime="2018-11-14T14:14:22.000Z">2018-11-14</time></div>
<a href="/2018/11/14/interview/" class="has-link-black-ter is-size-6"></a>
<p class="is-size-7 is-uppercase">
</p>
</div>
</div>
</article>
<article class="media">
<a href="/2018/11/06/storage/" class="media-left">
<p class="image is-64x64">
<img class="thumbnail" src="/images/thumbnail.svg" alt="cookie,sessionStorage,localStorage">
</p>
</a>
<div class="media-content">
<div class="content">
<div><time class="has-text-grey is-size-7 is-uppercase" datetime="2018-11-06T08:04:04.000Z">2018-11-06</time></div>
<a href="/2018/11/06/storage/" class="has-link-black-ter is-size-6">cookie,sessionStorage,localStorage</a>
<p class="is-size-7 is-uppercase">
</p>
</div>
</div>
</article>
<article class="media">
<a href="/2018/07/13/third/" class="media-left">
<p class="image is-64x64">
<img class="thumbnail" src="/images/thumbnail.svg" alt="跨域问题详解">
</p>
</a>
<div class="media-content">
<div class="content">
<div><time class="has-text-grey is-size-7 is-uppercase" datetime="2018-07-12T16:00:00.000Z">2018-07-13</time></div>
<a href="/2018/07/13/third/" class="has-link-black-ter is-size-6">跨域问题详解</a>
<p class="is-size-7 is-uppercase">
</p>
</div>
</div>
</article>
</div>
</div>
<div class="card widget">
<div class="card-content">
<div class="menu">
<h3 class="menu-label">
文档
</h3>
<ul class="menu-list">
<li>
<a class="level is-marginless" href="/archives/2018/11/">
<span class="level-start">
<span class="level-item">十一月 2018</span>
</span>
<span class="level-end">
<span class="level-item tag">4</span>
</span>
</a>
</li>
<li>
<a class="level is-marginless" href="/archives/2018/07/">
<span class="level-start">
<span class="level-item">七月 2018</span>
</span>
<span class="level-end">
<span class="level-item tag">1</span>
</span>
</a>
</li>
</ul>
</div>
</div>
</div>
<div class="card widget">
<div class="card-content">
<div class="menu">
<h3 class="menu-label">
标签
</h3>
<ul class="menu-list">
</ul>
</div>
</div>
</div>
</div>
</div>
</div>
</section>
<footer class="footer">
<div class="container">
<div class="level">
<div class="level-start has-text-centered-mobile">
<a class="footer-logo is-block has-mb-6" href="/">
<img src="/images/logo.svg" alt="" height="28">
</a>
<p class="is-size-7">
© 2019 Geminiknight
</p>
</div>
<div class="level-end">
</div>
</div>
</div>
</footer>
<script src="https://cdn.jsdelivr.net/npm/jquery@3.3.1/dist/jquery.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/moment@2.22.2/min/moment-with-locales.min.js"></script>
<script>moment.locale("zh-CN");</script>
<script src="https://cdn.jsdelivr.net/npm/lightgallery@1.6.8/dist/js/lightgallery.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/justifiedGallery@3.7.0/dist/js/jquery.justifiedGallery.min.js"></script>
<script>
(function ($) {
$(document).ready(function () {
if (typeof($.fn.lightGallery) === 'function') {
$('.article').lightGallery({ selector: '.gallery-item' });
}
if (typeof($.fn.justifiedGallery) === 'function') {
$('.justified-gallery').justifiedGallery();
}
});
})(jQuery);
</script>
<div id="outdated">
<h6>Your browser is out-of-date!</h6>
<p>Update your browser to view this website correctly. <a id="btnUpdateBrowser" href="http://outdatedbrowser.com/">Update my browser now </a></p>
<p class="last"><a href="#" id="btnCloseUpdateBrowser" title="Close">×</a></p>
</div>
<script src="https://cdn.jsdelivr.net/npm/outdatedbrowser@1.1.5/outdatedbrowser/outdatedbrowser.min.js"></script>
<script>
$(document).ready(function () {
// plugin function, place inside DOM ready function
outdatedBrowser({
bgColor: '#f25648',
color: '#ffffff',
lowerThan: 'flex'
})
});
</script>
<script src="https://cdn.jsdelivr.net/npm/animejs@2.2.0/anime.js"></script>
<script>
function isIE() {
var ua = window.navigator.userAgent;
var msie = ua.indexOf('MSIE ');
var trident = ua.indexOf('Trident/');
return (msie > 0 || trident > 0);
}
$(document).ready(function () {
$('body').css('opacity', 1);
if (!isIE()) {
['.main > .column:first-child .card',
'.main > .column:nth-child(2) .card',
'.main > .column:last-child .card'].map(function(target) {
anime({
targets: target,
scale: [0.8, 1],
opacity: [0, 1],
duration: 300,
easing: 'easeOutSine',
delay: function(el, i, l) {
return i * 100;
}
})
});
anime({
targets: '.navbar-main',
translateY: [-100, 0],
opacity: [0, 1],
duration: 300,
easing: 'easeOutSine'
});
}
});
</script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.4/MathJax.js?config=TeX-MML-AM_CHTML"></script>
<script>
MathJax.Hub.Config({
"HTML-CSS": {matchFontHeight: false},
SVG: {matchFontHeight: false},
CommonHTML: {matchFontHeight: false}
});
</script>
<a id="back-to-top" class="card has-text-centered" title="回到顶端" href="javascript:;">
<i class="material-icons">keyboard_arrow_up</i>
</a>
<style>
#back-to-top {
position: fixed;
bottom: 20px;
width: 64px;
padding: 8px 0;
transition: 0.4s ease opacity, 0.4s ease transform;
opacity: 0;
font-size: 0;
transform: translateY(120px);
}
#back-to-top.fade-in {
opacity: 1;
}
#back-to-top.rise-up {
transform: translateY(0);
}
@media screen and (max-width: 1087px) {
#back-to-top {
right: 1rem;
}
}
@media screen and (max-width: 768px) {
#back-to-top {
right: .75rem;
}
}
</style>
<script>
$(document).ready(function () {
var $button = $('#back-to-top');
var $mainColumn = $('.main .has-order-2');
var $leftColumn = $('.main .has-order-1');
var $rightColumn = $('.main .has-order-3');
var lastScrollTop = 0;
function update() {
// desktop mode or tablet mode with only right sidebar enabled
if (window.innerWidth > 1077 || (window.innerWidth > 768 && $leftColumn.length === 0 && $rightColumn.length === 1)) {
var padding = ($mainColumn.outerWidth() - $mainColumn.width()) / 2;
var left = $mainColumn.offset().left + $mainColumn.outerWidth() + padding;
left = Math.min(left, document.documentElement.clientWidth - $button.outerWidth(true) - padding);
$button.css('left', left);
var minScrollTop = 0;
if ($rightColumn.length > 0) {
minScrollTop = Math.max.apply(null, $rightColumn.find('.widget').map(function () {
return $(this).offset().top + $(this).outerHeight(true);
}));
}
if ($(window).scrollTop() + $(window).height() >= minScrollTop + padding + $button.outerHeight(true)) {
$button.addClass('fade-in');
} else {
$button.removeClass('fade-in');
}
$button.addClass('rise-up');
} else {
// mobile and tablet mode
$button.addClass('fade-in');
$button.css('left', '');
var scrollTop = $(window).scrollTop();
if (scrollTop > lastScrollTop || scrollTop === 0) {
$('#back-to-top').removeClass('rise-up');
} else {
$('#back-to-top').addClass('rise-up');
}
lastScrollTop = scrollTop;
}
}
update();
$(window).resize(update);
$(window).scroll(update);
$('#back-to-top').on('click', function () {
$('body, html').animate({ scrollTop: 0 }, 400);
});
});