forked from typescript-kr/typescript-kr.github.io
-
Notifications
You must be signed in to change notification settings - Fork 0
/
Declaration Merging.html
1236 lines (644 loc) Β· 60.4 KB
/
Declaration Merging.html
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="" >
<head>
<meta charset="UTF-8">
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
<title>μ μΈ λ³ν© Β· GitBook</title>
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="description" content="">
<meta name="generator" content="GitBook 3.2.3">
<meta property="og:title" content="TypeScript νκΈ λ¬Έμ">
<meta property="og:image" content="https://avatars1.githubusercontent.com/u/37781342?s=200&v=4">
<meta property="og:description" content="TypeScript νκΈ λ²μ λ¬Έμμ
λλ€">
<link rel="stylesheet" href="../gitbook/style.css">
<link rel="stylesheet" href="../gitbook/gitbook-plugin-highlight-1/website.css">
<link rel="stylesheet" href="../gitbook/gitbook-plugin-forkmegithub/plugin.css">
<link rel="stylesheet" href="../gitbook/gitbook-plugin-highlight/website.css">
<link rel="stylesheet" href="../gitbook/gitbook-plugin-search/search.css">
<link rel="stylesheet" href="../gitbook/gitbook-plugin-fontsettings/website.css">
<link rel="stylesheet" href="../assets/css/website.css">
<link rel="stylesheet" type="text/css" href="../assets/css/atom-one-dark.css" />
<meta name="HandheldFriendly" content="true"/>
<meta name="viewport" content="width=device-width, initial-scale=1, user-scalable=no">
<meta name="apple-mobile-web-app-capable" content="yes">
<meta name="apple-mobile-web-app-status-bar-style" content="black">
<link rel="apple-touch-icon-precomposed" sizes="152x152" href="../gitbook/images/apple-touch-icon-precomposed-152.png">
<link rel="shortcut icon" href="../gitbook/images/favicon.ico" type="image/x-icon">
<link rel="next" href="JSX.html" />
<link rel="prev" href="Module Resolution.html" />
</head>
<body>
<div class="book">
<div class="book-summary">
<div id="book-search-input" role="search">
<input type="text" placeholder="Type to search" />
</div>
<nav role="navigation">
<ul class="summary">
<li class="chapter " data-level="1.1" data-path="../">
<a href="../">
μκ°
</a>
</li>
<li class="header">νν 리μΌ</li>
<li class="chapter " data-level="2.1" data-path="tutorials/TypeScript in 5 minutes.html">
<a href="tutorials/TypeScript in 5 minutes.html">
5λΆ μμ 보λ TypeScript
</a>
</li>
<li class="chapter " data-level="2.2" data-path="tutorials/ASP.NET Core.html">
<a href="tutorials/ASP.NET Core.html">
ASP.NET Core
</a>
</li>
<li class="chapter " data-level="2.3" data-path="tutorials/Gulp.html">
<a href="tutorials/Gulp.html">
κ±Έν
</a>
</li>
<li class="chapter " data-level="2.4" data-path="tutorials/Migrating from JavaScript.html">
<a href="tutorials/Migrating from JavaScript.html">
JavaScriptμμ λ§μ΄κ·Έλ μ΄μ
</a>
</li>
<li class="chapter " data-level="2.5" data-path="tutorials/React & Webpack.html">
<a href="tutorials/React & Webpack.html">
리μ‘νΈ & μΉν©
</a>
</li>
<li class="header">νΈλλΆ</li>
<li class="chapter " data-level="3.1" data-path="Basic Types.html">
<a href="Basic Types.html">
κΈ°λ³Έ νμ
</a>
</li>
<li class="chapter " data-level="3.2" data-path="Variable Declarations.html">
<a href="Variable Declarations.html">
λ³μ μ μΈ
</a>
</li>
<li class="chapter " data-level="3.3" data-path="Interfaces.html">
<a href="Interfaces.html">
μΈν°νμ΄μ€
</a>
</li>
<li class="chapter " data-level="3.4" data-path="Classes.html">
<a href="Classes.html">
ν΄λμ€
</a>
</li>
<li class="chapter " data-level="3.5" data-path="Functions.html">
<a href="Functions.html">
ν¨μ
</a>
</li>
<li class="chapter " data-level="3.6" data-path="Generics.html">
<a href="Generics.html">
μ λ€λ¦
</a>
</li>
<li class="chapter " data-level="3.7" data-path="Enums.html">
<a href="Enums.html">
μ΄κ±°ν
</a>
</li>
<li class="chapter " data-level="3.8" data-path="Type Inference.html">
<a href="Type Inference.html">
νμ
μΆλ‘
</a>
</li>
<li class="chapter " data-level="3.9" data-path="Type Compatibility.html">
<a href="Type Compatibility.html">
νμ
νΈνμ±
</a>
</li>
<li class="chapter " data-level="3.10" data-path="Advanced Types.html">
<a href="Advanced Types.html">
κ³ κΈ νμ
</a>
</li>
<li class="chapter " data-level="3.11" data-path="Symbols.html">
<a href="Symbols.html">
μ¬λ³Ό
</a>
</li>
<li class="chapter " data-level="3.12" data-path="Iterators and Generators.html">
<a href="Iterators and Generators.html">
μ΄ν°λ μ΄ν°μ μ λ€λ μ΄ν°
</a>
</li>
<li class="chapter " data-level="3.13" data-path="Modules.html">
<a href="Modules.html">
λͺ¨λ
</a>
</li>
<li class="chapter " data-level="3.14" data-path="Namespaces.html">
<a href="Namespaces.html">
λ€μμ€νμ΄μ€
</a>
</li>
<li class="chapter " data-level="3.15" data-path="Namespaces and Modules.html">
<a href="Namespaces and Modules.html">
λ€μμ€νμ΄μ€μ λͺ¨λ
</a>
</li>
<li class="chapter " data-level="3.16" data-path="Module Resolution.html">
<a href="Module Resolution.html">
λͺ¨λ ν΄μ
</a>
</li>
<li class="chapter active" data-level="3.17" data-path="Declaration Merging.html">
<a href="Declaration Merging.html">
μ μΈ λ³ν©
</a>
</li>
<li class="chapter " data-level="3.18" data-path="JSX.html">
<a href="JSX.html">
JSX
</a>
</li>
<li class="chapter " data-level="3.19" data-path="Decorators.html">
<a href="Decorators.html">
λ°μ½λ μ΄ν°
</a>
</li>
<li class="chapter " data-level="3.20" data-path="Mixins.html">
<a href="Mixins.html">
λ―Ήμ€μΈ
</a>
</li>
<li class="chapter " data-level="3.21" data-path="Triple-Slash Directives.html">
<a href="Triple-Slash Directives.html">
νΈλ¦¬ν-μ¬λμ μ§μμ
</a>
</li>
<li class="chapter " data-level="3.22" data-path="Type Checking JavaScript Files.html">
<a href="Type Checking JavaScript Files.html">
JavaScript νμΌ νμ
κ²μ¬
</a>
</li>
<li class="chapter " data-level="3.23" data-path="Utility Types.html">
<a href="Utility Types.html">
μ νΈλ¦¬ν° νμ
</a>
</li>
<li class="header">μ μΈ νμΌ</li>
<li class="chapter " data-level="4.1" data-path="declaration files/Introduction.html">
<a href="declaration files/Introduction.html">
μκ°
</a>
</li>
<li class="chapter " data-level="4.2" data-path="declaration files/Library Structures.html">
<a href="declaration files/Library Structures.html">
Library Structures
</a>
</li>
<li class="chapter " data-level="4.3" data-path="declaration files/By Example.html">
<a href="declaration files/By Example.html">
By Example
</a>
</li>
<li class="chapter " data-level="4.4" data-path="declaration files/Do's and Don'ts.html">
<a href="declaration files/Do's and Don'ts.html">
Do's and Don'ts
</a>
</li>
<li class="chapter " data-level="4.5" data-path="declaration files/Deep Dive.html">
<a href="declaration files/Deep Dive.html">
Deep Dive
</a>
</li>
<li class="chapter " data-level="4.6" data-path="declaration files/Templates.html">
<a href="declaration files/Templates.html">
Templates
</a>
<ul class="articles">
<li class="chapter " data-level="4.6.1" data-path="declaration files/templates/global-modifying-module.d.ts.html">
<a href="declaration files/templates/global-modifying-module.d.ts.html">
global-modifying-module.d.ts
</a>
</li>
<li class="chapter " data-level="4.6.2" data-path="declaration files/templates/global-plugin.d.ts.html">
<a href="declaration files/templates/global-plugin.d.ts.html">
global-plugin.d.ts
</a>
</li>
<li class="chapter " data-level="4.6.3" data-path="declaration files/templates/global.d.ts.html">
<a href="declaration files/templates/global.d.ts.html">
global.d.ts
</a>
</li>
<li class="chapter " data-level="4.6.4" data-path="declaration files/templates/module-class.d.ts.html">
<a href="declaration files/templates/module-class.d.ts.html">
module-class.d.ts
</a>
</li>
<li class="chapter " data-level="4.6.5" data-path="declaration files/templates/module-function.d.ts.html">
<a href="declaration files/templates/module-function.d.ts.html">
module-function.d.ts
</a>
</li>
<li class="chapter " data-level="4.6.6" data-path="declaration files/templates/module-plugin.d.ts.html">
<a href="declaration files/templates/module-plugin.d.ts.html">
module-plugin.d.ts
</a>
</li>
<li class="chapter " data-level="4.6.7" data-path="declaration files/templates/module.d.ts.html">
<a href="declaration files/templates/module.d.ts.html">
module.d.ts
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="4.7" data-path="declaration files/Publishing.html">
<a href="declaration files/Publishing.html">
Publishing
</a>
</li>
<li class="chapter " data-level="4.8" data-path="declaration files/Consumption.html">
<a href="declaration files/Consumption.html">
Consumption
</a>
</li>
<li class="header">νλ‘μ νΈ νκ²½μ€μ </li>
<li class="chapter " data-level="5.1" data-path="tsconfig.json.html">
<a href="tsconfig.json.html">
tsconfig.json
</a>
</li>
<li class="chapter " data-level="5.2" data-path="Compiler Options.html">
<a href="Compiler Options.html">
μ»΄νμΌλ¬ μ΅μ
</a>
</li>
<li class="chapter " data-level="5.3" data-path="Project References.html">
<a href="Project References.html">
νλ‘μ νΈ λ νΌλ°μ€
</a>
</li>
<li class="chapter " data-level="5.4" data-path="Compiler Options in MSBuild.html">
<a href="Compiler Options in MSBuild.html">
MSBuildμμμ μ»΄νμΌλ¬ μ΅μ
</a>
</li>
<li class="chapter " data-level="5.5" data-path="Integrating with Build Tools.html">
<a href="Integrating with Build Tools.html">
λΉλ λꡬμ ν΅ν©
</a>
</li>
<li class="chapter " data-level="5.6" data-path="Nightly Builds.html">
<a href="Nightly Builds.html">
Nightly λΉλ
</a>
</li>
<li class="header">λ¦΄λ¦¬μ¦ λ
ΈνΈ</li>
<li class="chapter " data-level="6.1" data-path="release notes/TypeScript 3.8.html">
<a href="release notes/TypeScript 3.8.html">
TypeScript 3.8
</a>
</li>
<li class="divider"></li>
<li>
<a href="https://www.gitbook.com" target="blank" class="gitbook-link">
Published with GitBook
</a>
</li>
</ul>
</nav>
</div>
<div class="book-body">
<div class="body-inner">
<div class="book-header" role="navigation">
<!-- Title -->
<h1>
<i class="fa fa-circle-o-notch fa-spin"></i>
<a href=".." >μ μΈ λ³ν©</a>
</h1>
</div>
<div class="page-wrapper" tabindex="-1" role="main">
<div class="page-inner">
<div id="book-search-results">
<div class="search-noresults">
<section class="normal markdown-section">
<h1 id="소개-introduction">소개 (Introduction)</h1>
<p>TypeScript의 독특한 개념들 중 일부는 타입 레벨에서 JavaScript 객체의 형태를 설명합니다.
그중 TypeScript만의 특별한 예로 '선언 병합' 개념이 있습니다.
이 개념을 이해한다면 기존의 JavaScript와 작업을 할 때 이점이 많아집니다.
또한 이 개념은 고급 추상화 개념으로의 문을 열어줄 것입니다.</p>
<p>본론으로 돌아가서, "선언 병합"은 컴파일러가 같은 이름으로 선언된 두 개의 개별적인 선언을 하나의 정의로 병합하는 것을 뜻합니다.
이 병합된 정의는 원래 두 선언 각각의 기능을 모두 갖게 됩니다.
병합할 선언이 몇 개든 상관없습니다; 이 개념은 단지 두 개의 선언만 합치도록 제한하지 않습니다.</p>
<h1 id="기본-사용법-basic-concepts">기본 사용법 (Basic Concepts)</h1>
<p>TypeScript에서 선언은 네임스페이스, 타입, 값 중 한 종류 이상의 엔티티를 생성합니다.
네임스페이스-생성 선언은 점으로 구분된 표기법을 사용하여 접근할 이름을 가진 네임스페이스를 생성합니다.
타입-생성 선언은 선언된 형태로 표시되며 지정된 이름에 바인딩 된 타입을 생성합니다.
마지막으로 값-생성 선언은 출력된 JavaScript에서 확인할 수 있는 값을 생성합니다.</p>
<table>
<thead>
<tr>
<th>선언 타입</th>
<th style="text-align:center">네임스페이스</th>
<th style="text-align:center">타입</th>
<th style="text-align:center">값</th>
</tr>
</thead>
<tbody>
<tr>
<td>네임스페이스</td>
<td style="text-align:center">X</td>
<td style="text-align:center"></td>
<td style="text-align:center">X</td>
</tr>
<tr>
<td>클래스</td>
<td style="text-align:center"></td>
<td style="text-align:center">X</td>
<td style="text-align:center">X</td>
</tr>
<tr>
<td>열거형</td>
<td style="text-align:center"></td>
<td style="text-align:center">X</td>
<td style="text-align:center">X</td>
</tr>
<tr>
<td>인터페이스</td>
<td style="text-align:center"></td>
<td style="text-align:center">X</td>
<td style="text-align:center"></td>
</tr>
<tr>
<td>타입 별칭</td>
<td style="text-align:center"></td>
<td style="text-align:center">X</td>
<td style="text-align:center"></td>
</tr>
<tr>
<td>함수</td>
<td style="text-align:center"></td>
<td style="text-align:center"></td>
<td style="text-align:center">X</td>
</tr>
<tr>
<td>변수</td>
<td style="text-align:center"></td>
<td style="text-align:center"></td>
<td style="text-align:center">X</td>
</tr>
</tbody>
</table>
<p>각 선언으로 생성된 결과물을 이해하면, 선언 병합을 할 때 병합된 결과물을 이해하는 데에 도움이 됩니다.</p>
<h1 id="인터페이스-병합-merging-interfaces">인터페이스 병합 (Merging Interfaces)</h1>
<p>가장 일반적이고 간단한 선언 병합 유형은 인터페이스 병합입니다.
가장 기본적인 수준에서, 병합은 각 선언의 멤버를 같은 이름의 인터페이스에 기계적으로 결합합니다.</p>
<pre><code class="lang-ts"><span class="cm-keyword">interface</span> <span class="cm-variable">Box</span> {
<span class="cm-variable">height</span>: <span class="cm-variable-3">number</span>;
<span class="cm-variable">width</span>: <span class="cm-variable-3">number</span>;
}
<span class="cm-keyword">interface</span> <span class="cm-variable">Box</span> {
<span class="cm-variable">scale</span>: <span class="cm-variable-3">number</span>;
}
<span class="cm-keyword">let</span> <span class="cm-variable">box</span>: <span class="cm-variable-3">Box</span> <span class="cm-operator">=</span> {<span class="cm-property">height</span>: <span class="cm-number">5</span>, <span class="cm-property">width</span>: <span class="cm-number">6</span>, <span class="cm-property">scale</span>: <span class="cm-number">10</span>};
</code></pre>
<p>각 인터페이스의 비-함수 멤버는 고유해야 합니다.
만약 고유하지 않다면, 모두 같은 타입이어야 합니다.
인터페이스가 같은 이름이지만 다른 타입을 가진 비-함수 멤버가 있을 경우, 컴파일러는 오류를 일으킵니다.</p>
<p>함수 멤버의 경우, 이름이 같을 경우 동일한 함수에 대한 오버로드하는 것으로 처리합니다.
또한 <code>A</code> 인터페이스와 나중의 <code>A</code> 인터페이스를 병합하는 경우, 두 번째 인터페이스가 더 높은 우선순위를 갖게 됩니다.</p>
<p>이 말은, 예를 들어:</p>
<pre><code class="lang-ts"><span class="cm-keyword">interface</span> <span class="cm-variable">Cloner</span> {
<span class="cm-variable">clone</span>(<span class="cm-variable">animal</span>: <span class="cm-variable">Animal</span>): <span class="cm-variable">Animal</span>;
}
<span class="cm-keyword">interface</span> <span class="cm-variable">Cloner</span> {
<span class="cm-variable">clone</span>(<span class="cm-variable">animal</span>: <span class="cm-variable">Sheep</span>): <span class="cm-variable">Sheep</span>;
}
<span class="cm-keyword">interface</span> <span class="cm-variable">Cloner</span> {
<span class="cm-variable">clone</span>(<span class="cm-variable">animal</span>: <span class="cm-variable">Dog</span>): <span class="cm-variable">Dog</span>;
<span class="cm-variable">clone</span>(<span class="cm-variable">animal</span>: <span class="cm-variable">Cat</span>): <span class="cm-variable">Cat</span>;
}
</code></pre>
<p>위의 세 인터페이스는 병합되어 다음과 같이 하나의 새로운 선언을 생성합니다:</p>
<pre><code class="lang-ts"><span class="cm-keyword">interface</span> <span class="cm-variable">Cloner</span> {
<span class="cm-variable">clone</span>(<span class="cm-variable">animal</span>: <span class="cm-variable">Dog</span>): <span class="cm-variable">Dog</span>;
<span class="cm-variable">clone</span>(<span class="cm-variable">animal</span>: <span class="cm-variable">Cat</span>): <span class="cm-variable">Cat</span>;
<span class="cm-variable">clone</span>(<span class="cm-variable">animal</span>: <span class="cm-variable">Sheep</span>): <span class="cm-variable">Sheep</span>;
<span class="cm-variable">clone</span>(<span class="cm-variable">animal</span>: <span class="cm-variable">Animal</span>): <span class="cm-variable">Animal</span>;
}
</code></pre>
<p>각 그룹의 요소는 동일한 순서를 유지하지만, 그룹 자체는 나중에 병합되어 오버로드 될수록 첫 번째에 위치하는 것에 유의하세요.</p>
<p>그러나 이 규칙엔 특수 시그니처라는 예외가 존재합니다.
시그니처에 <em>단일</em> 문자열 리터럴 타입(예: 문자열 리터럴의 유니언이 아닌 경우)인 매개변수가 있을 경우, 시그니처는 병합된 오버로드 목록의 맨 위로 올라오게 됩니다.</p>
<p>예를 들어, 아래의 인터페이스들이 병합됩니다:</p>
<pre><code class="lang-ts"><span class="cm-keyword">interface</span> <span class="cm-variable">Document</span> {
<span class="cm-variable">createElement</span>(<span class="cm-variable">tagName</span>: <span class="cm-variable-3">any</span>): <span class="cm-variable">Element</span>;
}
<span class="cm-keyword">interface</span> <span class="cm-variable">Document</span> {
<span class="cm-variable">createElement</span>(<span class="cm-variable">tagName</span>: <span class="cm-string">"div"</span>): <span class="cm-variable">HTMLDivElement</span>;
<span class="cm-variable">createElement</span>(<span class="cm-variable">tagName</span>: <span class="cm-string">"span"</span>): <span class="cm-variable">HTMLSpanElement</span>;
}
<span class="cm-keyword">interface</span> <span class="cm-variable">Document</span> {
<span class="cm-variable">createElement</span>(<span class="cm-variable">tagName</span>: <span class="cm-variable-3">string</span>): <span class="cm-variable">HTMLElement</span>;
<span class="cm-variable">createElement</span>(<span class="cm-variable">tagName</span>: <span class="cm-string">"canvas"</span>): <span class="cm-variable">HTMLCanvasElement</span>;
}
</code></pre>
<p><code>Document</code>의 병합된 선언은 다음과 같이 생성합니다:</p>
<pre><code class="lang-ts"><span class="cm-keyword">interface</span> <span class="cm-variable">Document</span> {
<span class="cm-variable">createElement</span>(<span class="cm-variable">tagName</span>: <span class="cm-string">"canvas"</span>): <span class="cm-variable">HTMLCanvasElement</span>;
<span class="cm-variable">createElement</span>(<span class="cm-variable">tagName</span>: <span class="cm-string">"div"</span>): <span class="cm-variable">HTMLDivElement</span>;
<span class="cm-variable">createElement</span>(<span class="cm-variable">tagName</span>: <span class="cm-string">"span"</span>): <span class="cm-variable">HTMLSpanElement</span>;
<span class="cm-variable">createElement</span>(<span class="cm-variable">tagName</span>: <span class="cm-variable-3">string</span>): <span class="cm-variable">HTMLElement</span>;
<span class="cm-variable">createElement</span>(<span class="cm-variable">tagName</span>: <span class="cm-variable-3">any</span>): <span class="cm-variable">Element</span>;
}
</code></pre>
<h1 id="네임스페이스-병합-merging-namespaces">네임스페이스 병합 (Merging Namespaces)</h1>
<p>인터페이스와 마찬가지로, 같은 이름을 가진 네임스페이스도 멤버를 병합합니다.
네임스페이스는 네임스페이스와 값을 둘 다 생성하기 때문에, 이들이 어떻게 병합하는지 이해해야 합니다.</p>
<p>네임스페이스를 병합하기 위해 각 네임스페이스에 선언된 내보낸 인터페이스로부터 타입 정의가 병합되며, 내부에 병합된 인터페이스 정의들이 있는 단일 네임스페이스를 형성됩니다.</p>
<p>네임스페이스 값을 병합하려면, 각 선언 위치에서 이미 지정된 이름의 네임스페이스가 있을 경우, 기존 네임스페이스에 두 번째 네임스페이스의 내보낸 멤버를 첫 번째에 추가하여 네임스페이스 값을 확장됩니다.</p>
<p>이 예제에서 <code>Animals</code>의 선언 병합:</p>
<pre><code class="lang-ts"><span class="cm-variable">namespace</span> <span class="cm-variable">Animals</span> {
<span class="cm-keyword">export</span> <span class="cm-keyword">class</span> <span class="cm-variable">Zebra</span> { }
}
<span class="cm-variable">namespace</span> <span class="cm-variable">Animals</span> {
<span class="cm-keyword">export</span> <span class="cm-keyword">interface</span> <span class="cm-variable">Legged</span> { <span class="cm-variable">numberOfLegs</span>: <span class="cm-variable-3">number</span>; }
<span class="cm-keyword">export</span> <span class="cm-keyword">class</span> <span class="cm-variable">Dog</span> { }
}
</code></pre>
<p>다음과 같습니다:</p>
<pre><code class="lang-ts"><span class="cm-variable">namespace</span> <span class="cm-variable">Animals</span> {
<span class="cm-keyword">export</span> <span class="cm-keyword">interface</span> <span class="cm-variable">Legged</span> { <span class="cm-variable">numberOfLegs</span>: <span class="cm-variable-3">number</span>; }