{"id":4832,"date":"2023-01-05T10:40:53","date_gmt":"2023-01-05T02:40:53","guid":{"rendered":"https:\/\/badgameshow.com\/steven\/?p=4832"},"modified":"2023-01-05T10:40:53","modified_gmt":"2023-01-05T02:40:53","slug":"%e5%ad%b8%e7%bf%92typescript%e6%a2%9d%e4%bb%b6%e9%a1%9e%e5%9e%8b%ef%bc%9a%e6%8e%8c%e6%8f%a1%e6%a2%9d%e4%bb%b6%e9%a1%9e%e5%9e%8b%e7%9a%84%e5%9f%ba%e7%a4%8e%e7%9f%a5%e8%ad%98","status":"publish","type":"post","link":"https:\/\/badgameshow.com\/steven\/typescript\/%e5%ad%b8%e7%bf%92typescript%e6%a2%9d%e4%bb%b6%e9%a1%9e%e5%9e%8b%ef%bc%9a%e6%8e%8c%e6%8f%a1%e6%a2%9d%e4%bb%b6%e9%a1%9e%e5%9e%8b%e7%9a%84%e5%9f%ba%e7%a4%8e%e7%9f%a5%e8%ad%98\/","title":{"rendered":"\u5b78\u7fd2TypeScript\u689d\u4ef6\u985e\u578b\uff1a\u638c\u63e1\u689d\u4ef6\u985e\u578b\u7684\u57fa\u790e\u77e5\u8b58"},"content":{"rendered":"

<\/p>\n

\u4ec0\u9ebc\u662f TypeScript \u6761\u4ef6\u7c7b\u578b(conditional type)<\/h1>\n

TypeScript \u6761\u4ef6\u7c7b\u578b(conditional type)\u662f\u4e00\u7a2e\u5728 TypeScript \u4e2d\u53ef\u4ee5\u4f7f\u7528\u7684\u7279\u6b8a\u985e\u578b\uff0c\u5b83\u53ef\u4ee5\u6839\u64da\u689d\u4ef6\u4f86\u6c7a\u5b9a\u6700\u7d42\u7684\u985e\u578b\u3002\u5b83\u53ef\u4ee5\u8b93\u958b\u767c\u8005\u5728\u7de8\u5beb\u4ee3\u78bc\u6642\u66f4\u52a0\u7cbe\u78ba\u5730\u63a7\u5236\u985e\u578b\uff0c\u4ee5\u6eff\u8db3\u61c9\u7528\u7a0b\u5e8f\u7684\u9700\u6c42\u3002<\/p>\n

\u4f7f\u7528 TypeScript \u6761\u4ef6\u7c7b\u578b\u7684\u57fa\u672c\u8a9e\u6cd5<\/h2>\n

TypeScript \u6761\u4ef6\u985e\u578b\u7684\u57fa\u672c\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n

T extends U ? X : Y\n<\/code><\/pre>\n
\u5176\u4e2d\uff0cT \u662f\u4e00\u500b\u985e\u578b\uff0cU \u662f\u4e00\u500b\u985e\u578b\uff0cX \u662f\u4e00\u500b\u985e\u578b\uff0cY \u662f\u4e00\u500b\u985e\u578b\u3002\u5982\u679c T \u7e7c\u627f\u81ea U\uff0c\u5247\u6700\u7d42\u7684\u985e\u578b\u70ba X\uff0c\u5426\u5247\u70ba Y\u3002<\/p>\n
\u4f7f\u7528 TypeScript \u6761\u4ef6\u7c7b\u578b\u7684\u793a\u4f8b<\/h2>\n
\u8b93\u6211\u5011\u4f86\u770b\u4e00\u500b\u4f7f\u7528 TypeScript \u6761\u4ef6\u985e\u578b\u7684\u793a\u4f8b\uff1a<\/p>\n
type IsString<T> = T extends string ? true : false;\n\nlet a: IsString<string> = true; \/\/ true\nlet b: IsString<number> = false; \/\/ false\n<\/code><\/pre>\n
\u5728\u4e0a\u9762\u7684\u793a\u4f8b\u4e2d\uff0c\u6211\u5011\u5b9a\u7fa9\u4e86\u4e00\u500b\u540d\u70ba IsString \u7684\u985e\u578b\uff0c\u5b83\u63a5\u53d7\u4e00\u500b\u6cdb\u578b\u53c3\u6578 T\uff0c\u5982\u679c T \u7e7c\u627f\u81ea string\uff0c\u5247\u6700\u7d42\u7684\u985e\u578b\u70ba true\uff0c\u5426\u5247\u70ba false\u3002<\/p>\n
\u7e3d\u7d50<\/h2>\n
TypeScript \u6761\u4ef6\u7c7b\u578b(conditional type)\u662f\u4e00\u7a2e\u5728 TypeScript \u4e2d\u53ef\u4ee5\u4f7f\u7528\u7684\u7279\u6b8a\u985e\u578b\uff0c\u5b83\u53ef\u4ee5\u6839\u64da\u689d\u4ef6\u4f86\u6c7a\u5b9a\u6700\u7d42\u7684\u985e\u578b\uff0c\u8b93\u958b\u767c\u8005\u5728\u7de8\u5beb\u4ee3\u78bc\u6642\u66f4\u52a0\u7cbe\u78ba\u5730\u63a7\u5236\u985e\u578b\uff0c\u4ee5\u6eff\u8db3\u61c9\u7528\u7a0b\u5e8f\u7684\u9700\u6c42\u3002TypeScript \u6761\u4ef6\u985e\u578b\u7684\u57fa\u672c\u8a9e\u6cd5\u662f\uff1a<\/p>\n
T extends U ? X : Y<\/pre>\n
\uff0c\u5176\u4e2d\uff0cT \u662f\u4e00\u500b\u985e\u578b\uff0cU \u662f\u4e00\u500b\u985e\u578b\uff0cX \u662f\u4e00\u500b\u985e\u578b\uff0cY \u662f\u4e00\u500b\u985e\u578b\u3002\u5982\u679c T \u7e7c\u627f\u81ea U\uff0c\u5247\u6700\u7d42\u7684\u985e\u578b\u70ba X\uff0c\u5426\u5247\u70ba Y\u3002\u901a\u904e\u4f7f\u7528 TypeScript \u6761\u4ef6\u985e\u578b\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u66f4\u52a0\u7cbe\u78ba\u5730\u63a7\u5236\u985e\u578b\uff0c\u4ee5\u6eff\u8db3\u61c9\u7528\u7a0b\u5e8f\u7684\u9700\u6c42\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
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