{"type":"doc","content":[{"type":"paragraph","attrs":{"textAlign":null},"content":[{"type":"text","text":"В TypeScript можно указать "},{"type":"text","marks":[{"type":"bold"}],"text":"тип по умолчанию для generic-параметра"},{"type":"text","text":" — точно так же, как и для аргументов функции."},{"type":"hardBreak"},{"type":"text","text":"Это называется "},{"type":"text","marks":[{"type":"bold"}],"text":"default generic type parameter"},{"type":"text","text":"."}]},{"type":"horizontalRule"},{"type":"heading","attrs":{"textAlign":null,"level":2},"content":[{"type":"text","text":"🔹 Синтаксис"}]},{"type":"codeBlock","attrs":{"language":"javascript"},"content":[{"type":"text","text":"type MyType = ...\n"}]},{"type":"paragraph","attrs":{"textAlign":null},"content":[{"type":"text","text":"или для функции:"}]},{"type":"codeBlock","attrs":{"language":"javascript"},"content":[{"type":"text","text":"function myFunc(arg: T) { ... }\n"}]},{"type":"paragraph","attrs":{"textAlign":null},"content":[{"type":"text","text":"Если при использовании generic-типа/функции "},{"type":"text","marks":[{"type":"bold"}],"text":"тип явно не указан"},{"type":"text","text":", TypeScript возьмёт "},{"type":"text","marks":[{"type":"bold"}],"text":"значение по умолчанию"},{"type":"text","text":"."}]},{"type":"horizontalRule"},{"type":"heading","attrs":{"textAlign":null,"level":2},"content":[{"type":"text","text":"📘 Пример 1: тип по умолчанию в функции"}]},{"type":"codeBlock","attrs":{"language":"javascript"},"content":[{"type":"text","text":"function wrap(value: T): { data: T } {\n return { data: value };\n}\n\nwrap(\"hi\"); // T = string (по аргументу)\nwrap(42); // T = number (инференс)\nwrap(); // T = string (тип по умолчанию)\n"}]},{"type":"paragraph","attrs":{"textAlign":null},"content":[{"type":"text","text":"💡 Здесь, если TypeScript не может вывести тип "},{"type":"text","marks":[{"type":"code"}],"text":"T"},{"type":"text","text":", он берёт "},{"type":"text","marks":[{"type":"code"}],"text":"string"},{"type":"text","text":"."}]},{"type":"horizontalRule"},{"type":"heading","attrs":{"textAlign":null,"level":2},"content":[{"type":"text","text":"📘 Пример 2: тип по умолчанию в type-определении"}]},{"type":"codeBlock","attrs":{"language":"javascript"},"content":[{"type":"text","text":"type Response = {\n data: T;\n success: boolean;\n};\n\nconst r1: Response = { data: \"ok\", success: true }; // T = string\nconst r2: Response = { data: 200, success: true }; // T = number\n"}]},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"textAlign":null},"content":[{"type":"text","text":"Часто применяют, чтобы упростить использование типа без необходимости явно указывать generic."}]}]},{"type":"horizontalRule"},{"type":"heading","attrs":{"textAlign":null,"level":2},"content":[{"type":"text","text":"📘 Пример 3: несколько параметров с разными значениями по умолчанию"}]},{"type":"codeBlock","attrs":{"language":"javascript"},"content":[{"type":"text","text":"type Pair = [T, U];\n\nconst a: Pair = [\"age\", 25]; // [string, number]\nconst b: Pair = [true, \"ok\"]; // [boolean, string]\n"}]},{"type":"horizontalRule"},{"type":"heading","attrs":{"textAlign":null,"level":2},"content":[{"type":"text","text":"📘 Пример 4: использование в интерфейсах"}]},{"type":"codeBlock","attrs":{"language":"javascript"},"content":[{"type":"text","text":"interface ApiResponse {\n data: T;\n error?: string;\n}\n\nconst res1: ApiResponse = { data: \"ok\" }; // T = any\nconst res2: ApiResponse = { data: 42 }; // T = number\n"}]},{"type":"horizontalRule"},{"type":"heading","attrs":{"textAlign":null,"level":2},"content":[{"type":"text","text":"📘 Пример 5: в функциях с ограничением ("},{"type":"text","marks":[{"type":"code"}],"text":"extends"},{"type":"text","text":")"}]},{"type":"codeBlock","attrs":{"language":"javascript"},"content":[{"type":"text","text":"function getValue(obj: T): T {\n return obj;\n}\n\ngetValue(); // T = { id: number }\n"}]},{"type":"horizontalRule"},{"type":"heading","attrs":{"textAlign":null,"level":2},"content":[{"type":"text","text":"⚠️ Важно"}]},{"type":"orderedList","attrs":{"start":1,"type":null},"content":[{"type":"listItem","content":[{"type":"paragraph","attrs":{"textAlign":null},"content":[{"type":"text","text":"Тип по умолчанию используется "},{"type":"text","marks":[{"type":"bold"}],"text":"только если TypeScript не смог вывести тип"},{"type":"text","text":"."}]}]},{"type":"listItem","content":[{"type":"paragraph","attrs":{"textAlign":null},"content":[{"type":"text","text":"Если тип можно вывести по аргументу — значение по умолчанию "},{"type":"text","marks":[{"type":"bold"}],"text":"игнорируется"},{"type":"text","text":"."}]}]},{"type":"listItem","content":[{"type":"paragraph","attrs":{"textAlign":null},"content":[{"type":"text","text":"В списке generic-параметров "},{"type":"text","marks":[{"type":"bold"}],"text":"параметр с дефолтом должен идти после параметров без дефолта"},{"type":"text","text":":"}]},{"type":"codeBlock","attrs":{"language":"javascript"},"content":[{"type":"text","text":"// ✅\ntype Example = ...\n// ❌ Ошибка\ntype Bad = ...\n"}]}]}]},{"type":"horizontalRule"},{"type":"heading","attrs":{"textAlign":null,"level":2},"content":[{"type":"text","text":"✅ Итого"}]},{"type":"table","content":[{"type":"tableRow","content":[{"type":"tableHeader","attrs":{"colspan":1,"rowspan":1,"colwidth":null},"content":[{"type":"paragraph","attrs":{"textAlign":null},"content":[{"type":"text","text":"Возможность"}]}]},{"type":"tableHeader","attrs":{"colspan":1,"rowspan":1,"colwidth":null},"content":[{"type":"paragraph","attrs":{"textAlign":null},"content":[{"type":"text","text":"Пример"}]}]},{"type":"tableHeader","attrs":{"colspan":1,"rowspan":1,"colwidth":null},"content":[{"type":"paragraph","attrs":{"textAlign":null},"content":[{"type":"text","text":"Описание"}]}]}]},{"type":"tableRow","content":[{"type":"tableCell","attrs":{"colspan":1,"rowspan":1,"colwidth":null},"content":[{"type":"paragraph","attrs":{"textAlign":null},"content":[{"type":"text","text":"Тип по 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Тип по умолчанию в дженерике

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