{"id":137241,"date":"2022-08-28T06:00:58","date_gmt":"2022-08-27T21:00:58","guid":{"rendered":"https:\/\/anthem00.xsrv.jp\/2023_new_tcd\/?p=137241"},"modified":"2022-08-27T14:07:47","modified_gmt":"2022-08-27T05:07:47","slug":"javascript-prototype-method","status":"publish","type":"post","link":"https:\/\/anthem00.xsrv.jp\/2023_new_tcd\/2022\/08\/javascript-prototype-method.html","title":{"rendered":"\u3010JavaScript\u306e\u57fa\u672c\u3011\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u3068\u30e1\u30bd\u30c3\u30c9"},"content":{"rendered":"

JavaScript\u3067\u306f\u3001__proto__<\/code>\u30d7\u30ed\u30d1\u30c6\u30a3\u3092\u4f7f\u3063\u3066\u3001\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304c\u6301\u3064\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u306b\u30a2\u30af\u30bb\u30b9\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002
\n\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u3092\u78ba\u8a8d\u3059\u308b\u3060\u3051\u3067\u3042\u308c\u3070__proto__<\/code>\u306f\u4fbf\u5229\u3067\u3059\u304c\u3001\u5b9f\u969b\u306b\u306f\u53e4\u3044\u65b9\u6cd5\u3067\u3042\u308a\u975e\u63a8\u5968\u3068\u306a\u3063\u3066\u3044\u307e\u3059\u3002<\/p>\n

\u73fe\u5728\u3067\u306f__proto__<\/code>\u306e\u4ee3\u308f\u308a\u3068\u306a\u308b\u30e1\u30bd\u30c3\u30c9\u304c\u7528\u610f\u3055\u308c\u3066\u3044\u307e\u3059\u3002
\n\u305d\u3053\u3067\u4eca\u56de\u306f\u3001\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u306e\u78ba\u8a8d\u3084\u8a2d\u5b9a\u306e\u305f\u3081\u306e\u30e1\u30bd\u30c3\u30c9\u306b\u3064\u3044\u3066\u89e3\u8aac\u3057\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n

Object.create()<\/h2>\n

Object.create<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u65e2\u5b58\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u3068\u3057\u3066\u7d99\u627f\u3057\u3001\u65b0\u3057\u3044\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u4f5c\u6210\u3057\u307e\u3059\u3002<\/p>\n

\u7b2c\u4e00\u5f15\u6570\u306b\u6307\u5b9a\u3057\u305fprototype<\/code>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u7d99\u627f\u3057\u307e\u3059\u3002<\/p>\n

\n
Object.create(prototype);\r\n<\/code><\/pre>\n<\/div>\n
\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30ea\u30c6\u30e9\u30eb\u3067\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u4f5c\u6210\u3059\u308b\u3068\u3001\u540c\u6642\u306bObject.prototype<\/code>\u3092\u7d99\u627f\u3057\u307e\u3059\u3002\u3053\u308c\u3092Object.create<\/code>\u30e1\u30bd\u30c3\u30c9\u3067\u66f8\u304f\u3068\u6b21\u306e\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n
\n
\/\/ let obj = {} \u3068\u540c\u3058\r\nlet obj = Object.create(Object.prototype);\r\n<\/code><\/pre>\n<\/div>\n
\u3082\u3061\u308d\u3093toString<\/code>\u306a\u3069\u306eObject.prototype<\/code>\u306b\u7528\u610f\u3055\u308c\u3066\u3044\u308b\u30e1\u30bd\u30c3\u30c9\u3082\u4f7f\u7528\u3067\u304d\u307e\u3059\u3002
\n\u305d\u306e\u305f\u3081\u3001\u4ee5\u4e0b\u306f\u540c\u3058\u3082\u306e\u3068\u3057\u3066\u898b\u306a\u3055\u308c\u307e\u3059\u3002<\/p>\n
\n
let obj = Object.create(Object.prototype);\r\n\r\nconsole.log(obj.toString === Object.prototype.toString); \/\/ true\r\n<\/code><\/pre>\n<\/div>\n
\u4f8b\u3048\u3070\u3001user<\/code>\u3068\u3044\u3046\u540d\u524d\u306eObject<\/code>\u304c\u3042\u308b\u3068\u3057\u307e\u3059\u3002
\nuser<\/code>\u3092\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u3068\u3057\u3066\u3001\u65b0\u3057\u3044user1<\/code>\u3068\u3044\u3046\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u4f5c\u6210\u3059\u308b\u3068\u3053\u306e\u3088\u3046\u306b\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n
\n
let user = {\r\n  id: true\r\n};\r\n\r\n\/\/ user\u3092\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u3068\u3057\u3066\u65b0\u3057\u3044\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u4f5c\u6210\r\nlet user1 = Object.create(user);\r\n\r\nconsole.log(user1.id); \/\/ true\r\n<\/code><\/pre>\n<\/div>\n
\u307e\u305f\u3001Object.create<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u4efb\u610f\u3067\u7b2c\u4e8c\u5f15\u6570\u3092\u6307\u5b9a\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002
\n\u65b0\u3057\u3044\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306b\u30d7\u30ed\u30d1\u30c6\u30a3\u3092\u8ffd\u52a0\u3057\u305f\u3044\u969b\u306b\u8a18\u8ff0\u3057\u307e\u3059\u3002<\/p>\n
\n
Object.create(prototype[, descriptors]);\r\n<\/code><\/pre>\n<\/div>\n
\u3067\u306f\u3001user1<\/code>\u306b\u8ffd\u52a0\u306e\u30d7\u30ed\u30d1\u30c6\u30a3\u3092\u6307\u5b9a\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n
\n
let user = {\r\n  id: true\r\n};\r\n\r\n\/\/ \u65b0\u3057\u3044\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u4f5c\u6210\u6642\u306b\u30d7\u30ed\u30d1\u30c6\u30a3\u3092\u8ffd\u52a0\r\nlet user1 = Object.create(user, {\r\n  age: {\r\n    value: 20\r\n  }\r\n});\r\n\r\nconsole.log(user1.age); \/\/ 20\r\n<\/code><\/pre>\n<\/div>\n
user<\/code>\u306b\u306f\u7121\u304b\u3063\u305fage<\/code>\u3068\u3044\u3046\u30d7\u30ed\u30d1\u30c6\u30a3\u3092\u8ffd\u52a0\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3057\u305f\u3002<\/p>\n
Object.prototype\u3092\u7d99\u627f\u3057\u306a\u3044<\/h3>\n
Object<\/code>\u306f\u3001\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u4f5c\u6210\u6642\u306bObject.prototype<\/code>\u3092\u7d99\u627f\u3057\u307e\u3059\u3002
\n\u3057\u304b\u3057\u3001\u7d99\u627f\u3057\u305f\u304f\u306a\u3044\u5834\u5408\u306b\u306f\u3069\u3046\u3057\u305f\u3089\u826f\u3044\u306e\u3067\u3057\u3087\u3046\u304b\uff1f<\/p>\n
\u305d\u306e\u3088\u3046\u306a\u5834\u5408\u3001Object.create(null)<\/code>\u3067\u3001\u30d7\u30ed\u30d1\u30c6\u30a3\u3084\u30e1\u30bd\u30c3\u30c9\u3092\u6301\u305f\u306a\u3044\u7a7a\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u4f5c\u6210\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n
\n
let obj = Object.create(null);\r\n\r\nconsole.log(obj.hasOwnProperty); \/\/ undefined\r\n<\/code><\/pre>\n<\/div>\n
obj<\/code>\u306f\u3001Object.prototype<\/code>\u3092\u7d99\u627f\u3057\u3066\u3044\u306a\u3044\u305f\u3081\u3001\u305d\u306e\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u30e1\u30bd\u30c3\u30c9\u3067\u3042\u308bhasOwnProperty<\/code>\u3092\u547c\u3073\u51fa\u3059\u3053\u3068\u304c\u3067\u304d\u307e\u305b\u3093\u3002<\/p>\n
\u4ee3\u308f\u308a\u306b\u3001ES2022\u304b\u3089\u5c0e\u5165\u3055\u308c\u305fObject.hasOwn<\/code>\u30e1\u30bd\u30c3\u30c9\u304c\u4f7f\u3048\u307e\u3059\u3002\u5bfe\u8c61\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304cObject.prototype<\/code>\u3092\u7d99\u627f\u3057\u306a\u304f\u3066\u3082\u6709\u52b9\u3067\u3059\u3002<\/p>\n
\n
let obj = Object.create(null);\r\n\r\nconsole.log(Object.hasOwn(obj)); \/\/ false\r\n<\/code><\/pre>\n<\/div>\n
\u3053\u308c\u3067obj<\/code>\u306f\u3001\u30d7\u30ed\u30d1\u30c6\u30a3\u3092\u6301\u3063\u3066\u3044\u306a\u3044\u7a7a\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3067\u3042\u308b\u3053\u3068\u304c\u78ba\u8a8d\u3067\u304d\u307e\u3059\u3002<\/p>\n
Object.getPrototypeOf()<\/h2>\n
Object.getPrototypeOf<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u3092\u53d6\u5f97\u3057\u307e\u3059\u3002<\/p>\n
\u5f15\u6570\u306b\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u6307\u5b9a\u3059\u308b\u3068\u3001\u305d\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u304c\u8fd4\u308a\u307e\u3059\u3002<\/p>\n
\n
Object.getPrototypeOf(obj);\r\n<\/code><\/pre>\n<\/div>\n
\u3067\u306f\u3001\u5148\u307b\u3069\u4f5c\u6210\u3057\u305fuser1<\/code>\u306e\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u3092\u78ba\u8a8d\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n
\n
let user = {\r\n  id: true\r\n};\r\n\r\nlet user1 = Object.create(user);\r\n\r\n\/\/ user1\u306fuser\u306e\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u3092\u7d99\u627f\u3057\u3066\u3044\u308b\r\nconsole.log(Object.getPrototypeOf(user1)); \/\/ { id: true }\r\nconsole.log(Object.getPrototypeOf(user1) === user); \/\/ true\r\n<\/code><\/pre>\n<\/div>\n
user1<\/code>\u304cuser<\/code>\u306e\u5024\u3092\u53c2\u7167\u3057\u3066\u3044\u308b\uff08\u3068\u540c\u3058\uff09\u3067\u3042\u308b\u3053\u3068\u304c\u78ba\u8a8d\u3067\u304d\u307e\u3059\u3002<\/p>\n
Object.setPrototypeOf()<\/h2>\n
Object.setPrototypeOf<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u3092\u8a2d\u5b9a\u3057\u307e\u3059\u3002<\/p>\n
\u7b2c\u4e00\u5f15\u6570\u306b\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3001\u7b2c\u4e8c\u5f15\u6570\u306b\u8a2d\u5b9a\u3057\u305f\u3044\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u3092\u6307\u5b9a\u3057\u307e\u3059\u3002<\/p>\n
\n
Object.getPrototypeOf(obj, prototype);\r\n<\/code><\/pre>\n<\/div>\n
\u3053\u3053\u3067\u306f\u3001user1<\/code>\u306b\u5bfe\u3057\u3066\u3001\u65b0\u305f\u306b\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u3092\u8a2d\u5b9a\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002
\n\u307e\u305a\u3053\u306e\u6642\u70b9\u3067\u306f\u3001user1<\/code>\u3068user<\/code>\u304c\u540c\u3058\u3067\u3042\u308b\u3053\u3068\u304c\u78ba\u8a8d\u3067\u304d\u307e\u3059\u3002<\/p>\n
\n
let user = {\r\n  id: true\r\n};\r\n\r\nlet user1 = Object.create(user);\r\n\r\n\/\/ user1\u306fuser\u306e\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u3092\u7d99\u627f\u3057\u3066\u3044\u308b\r\nconsole.log(Object.getPrototypeOf(user1) === user); \/\/ true\r\n<\/code><\/pre>\n<\/div>\n
\u3067\u306f\u3001\u7b2c\u4e00\u5f15\u6570\u306buser1<\/code>\u3001\u7b2c\u4e8c\u5f15\u6570\u306buser_new<\/code>\u3092\u8a2d\u5b9a\u3057\u3066\u3001user1<\/code>\u306e\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u3092\u5909\u66f4\u3057\u3066\u307f\u307e\u3059\u3002<\/p>\n
\n
let user_new = {\r\n  age: 20\r\n};\r\n\r\n\/\/ user1\u306e\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u3092user_new\u306b\u5909\u66f4\r\nObject.setPrototypeOf(user1, user_new);\r\n\r\nconsole.log(Object.getPrototypeOf(user1) === user_new); \/\/ true\r\n<\/code><\/pre>\n<\/div>\n
\u3053\u306e\u3088\u3046\u306b\u3001user1<\/code>\u306e\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u304cuser_new<\/code>\u306b\u5909\u66f4\u3055\u308c\u3066\u3044\u308b\u3053\u3068\u304c\u5206\u304b\u308a\u307e\u3059\u3002<\/p>\n
\u305d\u306e\u305f\u3081\u3001\u7d99\u627f\u5143\u3067\u3042\u3063\u305fuser<\/code>\u3068\u306f\u5225\u306e\u3082\u306e\u3068\u306a\u308a\u307e\u3059\u3002<\/p>\n
\n
console.log(Object.getPrototypeOf(user1) === user); \/\/ false\r\n<\/code><\/pre>\n<\/div>\n
\u307e\u3068\u3081<\/h2>\n
\u4eca\u56de\u306f\u3001\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u306e\u78ba\u8a8d\u3084\u8a2d\u5b9a\u3092\u884c\u3046\u305f\u3081\u306e\u30e1\u30bd\u30c3\u30c9\u306b\u3064\u3044\u3066\u89e3\u8aac\u3057\u307e\u3057\u305f\u3002<\/p>\n
\n
\/\/ \u30dd\u30a4\u30f3\u30c8\r\n* Object.create()\uff1a\u65e2\u5b58\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u3068\u3057\u3066\u7d99\u627f\u3057\u3066\u65b0\u3057\u3044\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u4f5c\u6210\u3059\u308b\r\n* Object.create(null)\uff1aObject.prototype\u3092\u7d99\u627f\u3057\u306a\u3044\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u4f5c\u6210\u3059\u308b\r\n* Object.getPrototypeOf()\uff1a\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u3092\u53d6\u5f97\u3059\u308b\r\n* Object.setPrototypeOf()\uff1a\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u3092\u8a2d\u5b9a\u3059\u308b\r\n<\/code><\/pre>\n<\/div>\n
\u5408\u308f\u305b\u3066\u8aad\u307f\u305f\u3044\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u30b7\u30ea\u30fc\u30ba<\/h2>\n
\u7b2c1\u56de\uff1a\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u306e\u4ed5\u7d44\u307f<\/strong><\/a>
\n\u7b2c2\u56de\uff1a\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3068\u30d7\u30ed\u30c8\u30bf\u30a4\u30d7\u7d99\u627f<\/strong><\/a>
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