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-cd31fc"},"children":[{"type":"text","value":"function"}]},{"type":"element","tag":"span","props":{"class":"ct-98b16c"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-939ffd"},"children":[{"type":"text","value":"isFish"}]},{"type":"element","tag":"span","props":{"class":"ct-98b16c"},"children":[{"type":"text","value":"("}]},{"type":"element","tag":"span","props":{"class":"ct-37efbc"},"children":[{"type":"text","value":"pet"}]},{"type":"element","tag":"span","props":{"class":"ct-76b8fb"},"children":[{"type":"text","value":":"}]},{"type":"element","tag":"span","props":{"class":"ct-98b16c"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-473662"},"children":[{"type":"text","value":"Fish"}]},{"type":"element","tag":"span","props":{"class":"ct-98b16c"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-76b8fb"},"children":[{"type":"text","value":"|"}]},{"type":"element","tag":"span","props":{"class":"ct-98b16c"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-473662"},"children":[{"type":"text","value":"Bird"}]},{"type":"element","tag":"span","props":{"class":"ct-98b16c"},"children":[{"type":"text","value":")"}]},{"type":"element","tag":"span","props":{"class":"ct-76b8fb"},"children":[{"type":"text","value":":"}]},{"type":"element","tag":"span","props":{"class":"ct-98b16c"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-37efbc"},"children":[{"type":"text","value":"pet"}]},{"type":"element","tag":"span","props":{"class":"ct-98b16c"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-76b8fb"},"children":[{"type":"text","value":"is"}]},{"type":"element","tag":"span","props":{"class":"ct-98b16c"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-473662"},"children":[{"type":"text","value":"Fish"}]},{"type":"element","tag":"span","props":{"class":"ct-98b16c"},"children":[{"type":"text","value":" {"}]}]},{"type":"element","tag":"span","props":{"class":"line"},"children":[{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":"  "}]},{"type":"element","tag":"span","props":{"class":"ct-33e115"},"children":[{"type":"text","value":"return"}]},{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":" ("}]},{"type":"element","tag":"span","props":{"class":"ct-a623c6"},"children":[{"type":"text","value":"pet"}]},{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-33e115"},"children":[{"type":"text","value":"as"}]},{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-4b137d"},"children":[{"type":"text","value":"Fish"}]},{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":")."}]},{"type":"element","tag":"span","props":{"class":"ct-a623c6"},"children":[{"type":"text","value":"swim"}]},{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-33e115"},"children":[{"type":"text","value":"!=="}]},{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-dd21f4"},"children":[{"type":"text","value":"undefined"}]},{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":";"}]}]},{"type":"element","tag":"span","props":{"class":"line"},"children":[{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"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-6dfd9d"},"children":[{"type":"text","value":"const"}]},{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-ad109c"},"children":[{"type":"text","value":"pet"}]},{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-33e115"},"children":[{"type":"text","value":"="}]},{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":" "}]},{"type":"element","tag":"span","props":{"class":"ct-9b7624"},"children":[{"type":"text","value":"getSmallPet"}]},{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":"();"}]}]},{"type":"element","tag":"span","props":{"class":"line"},"children":[{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":" "}]}]},{"type":"element","tag":"span","props":{"class":"line"},"children":[{"type":"element","tag":"span","props":{"class":"ct-33e115"},"children":[{"type":"text","value":"if"}]},{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":" ("}]},{"type":"element","tag":"span","props":{"class":"ct-9b7624"},"children":[{"type":"text","value":"isFish"}]},{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":"("}]},{"type":"element","tag":"span","props":{"class":"ct-a623c6"},"children":[{"type":"text","value":"pet"}]},{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":")) {"}]}]},{"type":"element","tag":"span","props":{"class":"line"},"children":[{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":"  "}]},{"type":"element","tag":"span","props":{"class":"ct-a623c6"},"children":[{"type":"text","value":"pet"}]},{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":"."}]},{"type":"element","tag":"span","props":{"class":"ct-9b7624"},"children":[{"type":"text","value":"swim"}]},{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":"();"}]}]},{"type":"element","tag":"span","props":{"class":"line"},"children":[{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":"} "}]},{"type":"element","tag":"span","props":{"class":"ct-33e115"},"children":[{"type":"text","value":"else"}]},{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":" {"}]}]},{"type":"element","tag":"span","props":{"class":"line"},"children":[{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":"  "}]},{"type":"element","tag":"span","props":{"class":"ct-a623c6"},"children":[{"type":"text","value":"pet"}]},{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":"."}]},{"type":"element","tag":"span","props":{"class":"ct-9b7624"},"children":[{"type":"text","value":"fly"}]},{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":"();"}]}]},{"type":"element","tag":"span","props":{"class":"line"},"children":[{"type":"element","tag":"span","props":{"class":"ct-d4fbff"},"children":[{"type":"text","value":"}"}]}]}]}]}]},{"type":"element","tag":"style","children":[{"type":"text","value":".ct-9b7624{color:#D2A8FF}.ct-ad109c{color:#79C0FF}.ct-6dfd9d{color:#FF7B72}.ct-dd21f4{color:#79C0FF}.ct-4b137d{color:#FFA657}.ct-a623c6{color:#C9D1D9}.ct-33e115{color:#FF7B72}.ct-d4fbff{color:#C9D1D9}.ct-473662{color:#FFA657}.ct-76b8fb{color:#FF7B72}.ct-37efbc{color:#FFA657}.ct-939ffd{color:#D2A8FF}.ct-98b16c{color:#C9D1D9}.ct-cd31fc{color:#FF7B72}.light .ct-cd31fc{color:#073642}.light .ct-98b16c{color:#657B83}.light .ct-939ffd{color:#268BD2}.light .ct-37efbc{color:#657B83}.light .ct-76b8fb{color:#859900}.light .ct-473662{color:#268BD2}.light .ct-d4fbff{color:#657B83}.light .ct-33e115{color:#859900}.light .ct-a623c6{color:#268BD2}.light .ct-4b137d{color:#268BD2}.light .ct-dd21f4{color:#B58900}.light .ct-6dfd9d{color:#073642}.light .ct-ad109c{color:#268BD2}.light .ct-9b7624{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"}