muerwre.github.io/api/_content/query/iZIUw8pCoM.json

{"_path":"/typescript/type-guards","_dir":"typescript","_draft":false,"_partial":false,"_locale":"en","_empty":false,"title":"Type Guards","description":"Useful for type checking at compile and run time:","excerpt":{"type":"root","children":[{"type":"element","tag":"p","props":{},"children":[{"type":"text","value":"Useful for type checking at compile and run time:"}]},{"type":"element","tag":"code","props":{"code":"function isFish(pet: Fish | Bird): pet is Fish {\n  return (pet as Fish).swim !== undefined;\n}\n","language":"typescript"},"children":[{"type":"element","tag":"pre","props":{},"children":[{"type":"element","tag":"code","props":{"__ignoreMap":""},"children":[{"type":"text","value":"function isFish(pet: Fish | Bird): pet is Fish {\n  return (pet as Fish).swim !== undefined;\n}\n"}]}]}]},{"type":"element","tag":"p","props":{},"children":[{"type":"text","value":"Usage:"}]},{"type":"element","tag":"code","props":{"code":"const pet = getSmallPet();\n \nif (isFish(pet)) {\n  pet.swim();\n} else {\n  pet.fly();\n}\n","language":"typescript"},"children":[{"type":"element","tag":"pre","props":{},"children":[{"type":"element","tag":"code","props":{"__ignoreMap":""},"children":[{"type":"text","value":"const pet = getSmallPet();\n \nif (isFish(pet)) {\n  pet.swim();\n} else {\n  pet.fly();\n}\n"}]}]}]}]},"body":{"type":"root","children":[{"type":"element","tag":"p","props":{},"children":[{"type":"text","value":"Useful for type checking at compile and run time:"}]},{"type":"element","tag":"code","props":{"code":"function isFish(pet: Fish | Bird): pet is Fish {\n  return (pet as Fish).swim !== undefined;\n}\n","language":"typescript"},"children":[{"type":"element","tag":"pre","props":{},"children":[{"type":"element","tag":"code","props":{"__ignoreMap":""},"children":[{"type":"element","tag":"span","props":{"class":"line"},"children":[{"type":"element","tag":"span","props":{"class":"ct-e6988d"},"children":[{"type":"text","value":"function"}]},{"type":"element","tag":"span","props":{"class":"ct-e1ee51"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-68061a"},"children":[{"type":"text","value":"isFish"}]},{"type":"element","tag":"span","props":{"class":"ct-e1ee51"},"children":[{"type":"text","value":"("}]},{"type":"element","tag":"span","props":{"class":"ct-b5a0e2"},"children":[{"type":"text","value":"pet"}]},{"type":"element","tag":"span","props":{"class":"ct-f141b4"},"children":[{"type":"text","value":":"}]},{"type":"element","tag":"span","props":{"class":"ct-e1ee51"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-5d2456"},"children":[{"type":"text","value":"Fish"}]},{"type":"element","tag":"span","props":{"class":"ct-e1ee51"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-f141b4"},"children":[{"type":"text","value":"|"}]},{"type":"element","tag":"span","props":{"class":"ct-e1ee51"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-5d2456"},"children":[{"type":"text","value":"Bird"}]},{"type":"element","tag":"span","props":{"class":"ct-e1ee51"},"children":[{"type":"text","value":")"}]},{"type":"element","tag":"span","props":{"class":"ct-f141b4"},"children":[{"type":"text","value":":"}]},{"type":"element","tag":"span","props":{"class":"ct-e1ee51"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-b5a0e2"},"children":[{"type":"text","value":"pet"}]},{"type":"element","tag":"span","props":{"class":"ct-e1ee51"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-f141b4"},"children":[{"type":"text","value":"is"}]},{"type":"element","tag":"span","props":{"class":"ct-e1ee51"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-5d2456"},"children":[{"type":"text","value":"Fish"}]},{"type":"element","tag":"span","props":{"class":"ct-e1ee51"},"children":[{"type":"text","value":" {"}]}]},{"type":"element","tag":"span","props":{"class":"line"},"children":[{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":"  "}]},{"type":"element","tag":"span","props":{"class":"ct-359d96"},"children":[{"type":"text","value":"return"}]},{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":" ("}]},{"type":"element","tag":"span","props":{"class":"ct-ba0a2b"},"children":[{"type":"text","value":"pet"}]},{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-359d96"},"children":[{"type":"text","value":"as"}]},{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-cc88bc"},"children":[{"type":"text","value":"Fish"}]},{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":")."}]},{"type":"element","tag":"span","props":{"class":"ct-ba0a2b"},"children":[{"type":"text","value":"swim"}]},{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-359d96"},"children":[{"type":"text","value":"!=="}]},{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-dbf28d"},"children":[{"type":"text","value":"undefined"}]},{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":";"}]}]},{"type":"element","tag":"span","props":{"class":"line"},"children":[{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":"}"}]}]}]}]}]},{"type":"element","tag":"p","props":{},"children":[{"type":"text","value":"Usage:"}]},{"type":"element","tag":"code","props":{"code":"const pet = getSmallPet();\n \nif (isFish(pet)) {\n  pet.swim();\n} else {\n  pet.fly();\n}\n","language":"typescript"},"children":[{"type":"element","tag":"pre","props":{},"children":[{"type":"element","tag":"code","props":{"__ignoreMap":""},"children":[{"type":"element","tag":"span","props":{"class":"line"},"children":[{"type":"element","tag":"span","props":{"class":"ct-bd6ed9"},"children":[{"type":"text","value":"const"}]},{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-d4f6a5"},"children":[{"type":"text","value":"pet"}]},{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-359d96"},"children":[{"type":"text","value":"="}]},{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-e3a74f"},"children":[{"type":"text","value":"getSmallPet"}]},{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":"();"}]}]},{"type":"element","tag":"span","props":{"class":"line"},"children":[{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":" "}]}]},{"type":"element","tag":"span","props":{"class":"line"},"children":[{"type":"element","tag":"span","props":{"class":"ct-359d96"},"children":[{"type":"text","value":"if"}]},{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":" ("}]},{"type":"element","tag":"span","props":{"class":"ct-e3a74f"},"children":[{"type":"text","value":"isFish"}]},{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":"("}]},{"type":"element","tag":"span","props":{"class":"ct-ba0a2b"},"children":[{"type":"text","value":"pet"}]},{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":")) {"}]}]},{"type":"element","tag":"span","props":{"class":"line"},"children":[{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":"  "}]},{"type":"element","tag":"span","props":{"class":"ct-ba0a2b"},"children":[{"type":"text","value":"pet"}]},{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":"."}]},{"type":"element","tag":"span","props":{"class":"ct-e3a74f"},"children":[{"type":"text","value":"swim"}]},{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":"();"}]}]},{"type":"element","tag":"span","props":{"class":"line"},"children":[{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":"} "}]},{"type":"element","tag":"span","props":{"class":"ct-359d96"},"children":[{"type":"text","value":"else"}]},{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":" {"}]}]},{"type":"element","tag":"span","props":{"class":"line"},"children":[{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":"  "}]},{"type":"element","tag":"span","props":{"class":"ct-ba0a2b"},"children":[{"type":"text","value":"pet"}]},{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":"."}]},{"type":"element","tag":"span","props":{"class":"ct-e3a74f"},"children":[{"type":"text","value":"fly"}]},{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":"();"}]}]},{"type":"element","tag":"span","props":{"class":"line"},"children":[{"type":"element","tag":"span","props":{"class":"ct-3d81ad"},"children":[{"type":"text","value":"}"}]}]}]}]}]},{"type":"element","tag":"style","children":[{"type":"text","value":".ct-e3a74f{color:#D2A8FF}.ct-d4f6a5{color:#79C0FF}.ct-bd6ed9{color:#FF7B72}.ct-dbf28d{color:#79C0FF}.ct-cc88bc{color:#FFA657}.ct-ba0a2b{color:#C9D1D9}.ct-359d96{color:#FF7B72}.ct-3d81ad{color:#C9D1D9}.ct-5d2456{color:#FFA657}.ct-f141b4{color:#FF7B72}.ct-b5a0e2{color:#FFA657}.ct-68061a{color:#D2A8FF}.ct-e1ee51{color:#C9D1D9}.ct-e6988d{color:#FF7B72}.light .ct-e6988d{color:#073642}.light .ct-e1ee51{color:#657B83}.light .ct-68061a{color:#268BD2}.light .ct-b5a0e2{color:#657B83}.light .ct-f141b4{color:#859900}.light .ct-5d2456{color:#268BD2}.light .ct-3d81ad{color:#657B83}.light .ct-359d96{color:#859900}.light .ct-ba0a2b{color:#268BD2}.light .ct-cc88bc{color:#268BD2}.light .ct-dbf28d{color:#B58900}.light .ct-bd6ed9{color:#073642}.light .ct-d4f6a5{color:#268BD2}.light .ct-e3a74f{color:#268BD2}"}]}],"toc":{"title":"","searchDepth":2,"depth":2,"links":[]}},"_type":"markdown","_id":"content:Typescript:Type guards.md","_source":"content","_file":"Typescript/Type guards.md","_extension":"md"}