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<\/p>\n

\u4f7f\u7528 TypeScript \u7c7b\u578b\u5b88\u536b\u51fd\u6570(type guards)<\/h1>\n

TypeScript \u7c7b\u578b\u5b88\u536b\u51fd\u6570(type guards)\u662f\u4e00\u7a2e\u6280\u8853\uff0c\u53ef\u4ee5\u5728\u7a0b\u5f0f\u78bc\u4e2d\u6aa2\u67e5\u503c\u7684\u985e\u578b\uff0c\u4e26\u6839\u64da\u6aa2\u67e5\u7d50\u679c\u66f4\u6539\u8a72\u503c\u7684\u985e\u578b\u3002\u5b83\u53ef\u4ee5\u8b93\u958b\u767c\u8005\u5728\u7a0b\u5f0f\u78bc\u4e2d\u66f4\u5bb9\u6613\u5730\u6aa2\u67e5\u548c\u64cd\u4f5c\u503c\u7684\u985e\u578b\uff0c\u5f9e\u800c\u63d0\u9ad8\u7a0b\u5f0f\u78bc\u7684\u53ef\u8b80\u6027\u548c\u53ef\u7dad\u8b77\u6027\u3002<\/p>\n

\u4ec0\u9ebc\u662f TypeScript \u7c7b\u578b\u5b88\u536b\u51fd\u6578\uff1f<\/h2>\n

TypeScript \u7c7b\u578b\u5b88\u536b\u51fd\u6578\u662f\u4e00\u7a2e\u6280\u8853\uff0c\u53ef\u4ee5\u5728\u7a0b\u5f0f\u78bc\u4e2d\u6aa2\u67e5\u503c\u7684\u985e\u578b\uff0c\u4e26\u6839\u64da\u6aa2\u67e5\u7d50\u679c\u66f4\u6539\u8a72\u503c\u7684\u985e\u578b\u3002\u5b83\u53ef\u4ee5\u8b93\u958b\u767c\u8005\u5728\u7a0b\u5f0f\u78bc\u4e2d\u66f4\u5bb9\u6613\u5730\u6aa2\u67e5\u548c\u64cd\u4f5c\u503c\u7684\u985e\u578b\uff0c\u5f9e\u800c\u63d0\u9ad8\u7a0b\u5f0f\u78bc\u7684\u53ef\u8b80\u6027\u548c\u53ef\u7dad\u8b77\u6027\u3002<\/p>\n

TypeScript \u7c7b\u578b\u5b88\u536b\u51fd\u6578\u53ef\u4ee5\u7528\u65bc\u6aa2\u67e5\u503c\u7684\u985e\u578b\uff0c\u4e26\u6839\u64da\u6aa2\u67e5\u7d50\u679c\u66f4\u6539\u8a72\u503c\u7684\u985e\u578b\u3002\u4f8b\u5982\uff0c\u5982\u679c\u60a8\u60f3\u6aa2\u67e5\u4e00\u500b\u503c\u662f\u5426\u70ba\u5b57\u7b26\u4e32\uff0c\u60a8\u53ef\u4ee5\u4f7f\u7528 TypeScript \u7c7b\u578b\u5b88\u536b\u51fd\u6578\u4f86\u6aa2\u67e5\u8a72\u503c\uff0c\u4e26\u6839\u64da\u6aa2\u67e5\u7d50\u679c\u66f4\u6539\u8a72\u503c\u7684\u985e\u578b\u3002<\/p>\n

<\/p>\n

\u5982\u4f55\u4f7f\u7528 TypeScript \u7c7b\u578b\u5b88\u536b\u51fd\u6578\uff1f<\/h2>\n

\u4f7f\u7528 TypeScript \u7c7b\u578b\u5b88\u536b\u51fd\u6578\u7684\u6b65\u9a5f\u5982\u4e0b\uff1a<\/p>\n

    \n
  1. \u5b9a\u7fa9\u4e00\u500b\u51fd\u6578\uff0c\u8a72\u51fd\u6578\u63a5\u53d7\u4e00\u500b\u53c3\u6578\uff0c\u4e26\u6aa2\u67e5\u8a72\u53c3\u6578\u7684\u985e\u578b\u3002<\/li>\n
  2. \u5982\u679c\u53c3\u6578\u7684\u985e\u578b\u7b26\u5408\u60a8\u7684\u8981\u6c42\uff0c\u5247\u8fd4\u56de true\uff0c\u5426\u5247\u8fd4\u56de false\u3002<\/li>\n
  3. \u5728\u7a0b\u5f0f\u78bc\u4e2d\u4f7f\u7528 if \u8a9e\u53e5\uff0c\u6839\u64da\u51fd\u6578\u7684\u8fd4\u56de\u503c\u66f4\u6539\u8a72\u503c\u7684\u985e\u578b\u3002<\/li>\n<\/ol>\n

    \u4ee5\u4e0b\u662f\u4e00\u500b\u7c21\u55ae\u7684\u793a\u4f8b\uff0c\u5c55\u793a\u4e86\u5982\u4f55\u4f7f\u7528 TypeScript \u7c7b\u578b\u5b88\u536b\u51fd\u6578\uff1a<\/p>\n

    \nfunction isString(value: any): value is string {\n    return typeof value === 'string';\n}\n\nlet value = 'Hello World';\n\nif (isString(value)) {\n    \/\/ value \u7684\u985e\u578b\u88ab\u66f4\u6539\u70ba string\n    console.log(value.toUpperCase());\n}\n<\/pre>\n
    \u5728\u4e0a\u9762\u7684\u793a\u4f8b\u4e2d\uff0c\u6211\u5011\u5b9a\u7fa9\u4e86\u4e00\u500b\u51fd\u6578 isString\uff0c\u8a72\u51fd\u6578\u63a5\u53d7\u4e00\u500b\u53c3\u6578\uff0c\u4e26\u6aa2\u67e5\u8a72\u53c3\u6578\u7684\u985e\u578b\u662f\u5426\u70ba\u5b57\u7b26\u4e32\u3002\u5982\u679c\u53c3\u6578\u7684\u985e\u578b\u70ba\u5b57\u7b26\u4e32\uff0c\u5247\u51fd\u6578\u8fd4\u56de true\uff0c\u5426\u5247\u8fd4\u56de false\u3002\u7136\u5f8c\uff0c\u6211\u5011\u4f7f\u7528 if \u8a9e\u53e5\uff0c\u6839\u64da\u51fd\u6578\u7684\u8fd4\u56de\u503c\u66f4\u6539\u8a72\u503c\u7684\u985e\u578b\u3002<\/p>\n
    \u7e3d\u7d50<\/h2>\n
    TypeScript \u7c7b\u578b\u5b88\u536b\u51fd\u6578\u662f\u4e00\u7a2e\u6280\u8853\uff0c\u53ef\u4ee5\u5728\u7a0b\u5f0f\u78bc\u4e2d\u6aa2\u67e5\u503c\u7684\u985e\u578b\uff0c\u4e26\u6839\u64da\u6aa2\u67e5\u7d50\u679c\u66f4\u6539\u8a72\u503c\u7684\u985e\u578b\u3002\u5b83\u53ef\u4ee5\u8b93\u958b\u767c\u8005\u5728\u7a0b\u5f0f\u78bc\u4e2d\u66f4\u5bb9\u6613\u5730\u6aa2\u67e5\u548c\u64cd\u4f5c\u503c\u7684\u985e\u578b\uff0c\u5f9e\u800c\u63d0\u9ad8\u7a0b\u5f0f\u78bc\u7684\u53ef\u8b80\u6027\u548c\u53ef\u7dad\u8b77\u6027\u3002\u4f7f\u7528 TypeScript \u7c7b\u578b\u5b88\u536b\u51fd\u6578\u7684\u6b65\u9a5f\u662f\uff1a\u5b9a\u7fa9\u4e00\u500b\u51fd\u6578\uff0c\u8a72\u51fd\u6578\u63a5\u53d7\u4e00\u500b\u53c3\u6578\uff0c\u4e26\u6aa2\u67e5\u8a72\u53c3\u6578\u7684\u985e\u578b\uff1b\u5982\u679c\u53c3\u6578\u7684\u985e\u578b\u7b26\u5408\u60a8\u7684\u8981\u6c42\uff0c\u5247\u8fd4\u56de true\uff0c\u5426\u5247\u8fd4\u56de false\uff1b\u6700\u5f8c\uff0c\u4f7f\u7528 if \u8a9e\u53e5\uff0c\u6839\u64da\u51fd\u6578\u7684\u8fd4\u56de\u503c\u66f4\u6539\u8a72\u503c\u7684\u985e\u578b\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
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